Carrier Selection in a Multi-Carrier Wireless Network

ABSTRACT

A wireless device receives a downlink control information (DCI) on a primary cell. The DCI may comprise a field instructing a wireless device to activate a secondary cell. The wireless device activates the secondary cell in response to receiving the DCI.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.15/273,341 entitled “Carrier selection in a multi-carrier wirelessnetwork” and filed on Sep. 22, 2016, which claims the benefit of U.S.Provisional Application No. 62/221,701, filed Sep. 22, 2015, each ofwhich is hereby incorporated by reference in its entirety.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

Examples of several of the various embodiments of the present inventionare described herein with reference to the drawings.

FIG. 1 is a diagram depicting example sets of OFDM subcarriers as per anaspect of an embodiment of the present invention.

FIG. 2 is a diagram depicting an example transmission time and receptiontime for two carriers in a carrier group as per an aspect of anembodiment of the present invention.

FIG. 3 is a diagram depicting OFDM radio resources as per an aspect ofan embodiment of the present invention.

FIG. 4 is a block diagram of a base station and a wireless device as peran aspect of an embodiment of the present invention.

FIG. 5A, FIG. 5B, FIG. 5C and FIG. 5D are example diagrams for uplinkand downlink signal transmission as per an aspect of an embodiment ofthe present invention.

FIG. 6 is an example diagram for a protocol structure with CA and DC asper an aspect of an embodiment of the present invention.

FIG. 7 is an example diagram for a protocol structure with CA and DC asper an aspect of an embodiment of the present invention.

FIG. 8 shows example TAG configurations as per an aspect of anembodiment of the present invention.

FIG. 9 is an example message flow in a random access process in asecondary TAG as per an aspect of an embodiment of the presentinvention.

DETAILED DESCRIPTION OF EMBODIMENTS

Example embodiments of the present invention enable operation of carrieraggregation. Embodiments of the technology disclosed herein may beemployed in the technical field of multicarrier communication systems.More particularly, the embodiments of the technology disclosed hereinmay relate to signal timing in a multicarrier communication systems.

The following Acronyms are used throughout the present disclosure:

ASIC application-specific integrated circuit

BPSK binary phase shift keying

CA carrier aggregation

CSI channel state information

CDMA code division multiple access

CSS common search space

CPLD complex programmable logic devices

CC component carrier

DL downlink

DCI downlink control information

DC dual connectivity

EPC evolved packet core

E-UTRAN evolved-universal terrestrial radio access network

FPGA field programmable gate arrays

FDD frequency division multiplexing

HDL hardware description languages

HARQ hybrid automatic repeat request

IE information element

LTE long term evolution

MCG master cell group

MeNB master evolved node B

MIB master information block

MAC media access control

MAC media access control

MME mobility management entity

NAS non-access stratum

OFDM orthogonal frequency division multiplexing

PDCP packet data convergence protocol

PDU packet data unit

PHY physical

PDCCH physical downlink control channel

PHICH physical HARQ indicator channel

PUCCH physical uplink control channel

PUSCH physical uplink shared channel

PCell primary cell

PCell primary cell

PCC primary component carrier

PSCell primary secondary cell

pTAG primary timing advance group

QAM quadrature amplitude modulation

QPSK quadrature phase shift keying

RBG Resource Block Groups

RLC radio link control

RRC radio resource control

RA random access

RB resource blocks

SCC secondary component carrier

SCell secondary cell

Scell secondary cells

SCG secondary cell group

SeNB secondary evolved node B

sTAGs secondary timing advance group

SDU service data unit

S-GW serving gateway

SRB signaling radio bearer

SC-OFDM single carrier-OFDM

SFN system frame number

SIB system information block

TAI tracking area identifier

TAT time alignment timer

TDD time division duplexing

TDMA time division multiple access

TA timing advance

TAG timing advance group

TB transport block

UL uplink

UE user equipment

VHDL VHSIC hardware Description Language

Example embodiments of the invention may be implemented using variousphysical layer modulation and transmission mechanisms. Exampletransmission mechanisms may include, but are not limited to: CDMA, OFDM,TDMA, Wavelet technologies, and/or the like. Hybrid transmissionmechanisms such as TDMA/CDMA, and OFDM/CDMA may also be employed.Various modulation schemes may be applied for signal transmission in thephysical layer. Examples of modulation schemes include, but are notlimited to: phase, amplitude, code, a combination of these, and/or thelike. An example radio transmission method may implement QAM using BPSK,QPSK, 16-QAM, 64-QAM, 256-QAM, and/or the like. Physical radiotransmission may be enhanced by dynamically or semi-dynamically changingthe modulation and coding scheme depending on transmission requirementsand radio conditions.

FIG. 1 is a diagram depicting example sets of OFDM subcarriers as per anaspect of an embodiment of the present invention. As illustrated in thisexample, arrow(s) in the diagram may depict a subcarrier in amulticarrier OFDM system. The OFDM system may use technology such asOFDM technology, DFTS-OFDM, SC-OFDM technology, or the like. Forexample, arrow 101 shows a subcarrier transmitting information symbols.FIG. 1 is for illustration purposes, and a typical multicarrier OFDMsystem may include more subcarriers in a carrier. For example, thenumber of subcarriers in a carrier may be in the range of 10 to 10,000subcarriers. FIG. 1 shows two guard bands 106 and 107 in a transmissionband. As illustrated in FIG. 1, guard band 106 is between subcarriers103 and subcarriers 104. The example set of subcarriers A 102 includessubcarriers 103 and subcarriers 104. FIG. 1 also illustrates an exampleset of subcarriers B 105. As illustrated, there is no guard band betweenany two subcarriers in the example set of subcarriers B 105. Carriers ina multicarrier OFDM communication system may be contiguous carriers,non-contiguous carriers, or a combination of both contiguous andnon-contiguous carriers.

FIG. 2 is a diagram depicting an example transmission time and receptiontime for two carriers as per an aspect of an embodiment of the presentinvention. A multicarrier OFDM communication system may include one ormore carriers, for example, ranging from 1 to 10 carriers. Carrier A 204and carrier B 205 may have the same or different timing structures.Although FIG. 2 shows two synchronized carriers, carrier A 204 andcarrier B 205 may or may not be synchronized with each other. Differentradio frame structures may be supported for FDD and TDD duplexmechanisms. FIG. 2 shows an example FDD frame timing. Downlink anduplink transmissions may be organized into radio frames 201. In thisexample, radio frame duration is 10 msec. Other frame durations, forexample, in the range of 1 to 100 msec may also be supported. In thisexample, each 10 ms radio frame 201 may be divided into ten equallysized subframes 202. Other subframe durations such as including 0.5msec, 1 msec, 2 msec, and 5 msec may also be supported. Subframe(s) mayconsist of two or more slots (e.g. slots 206 and 207). For the exampleof FDD, 10 subframes may be available for downlink transmission and 10subframes may be available for uplink transmissions in each 10 msinterval. Uplink and downlink transmissions may be separated in thefrequency domain. Slot(s) may include a plurality of OFDM symbols 203.The number of OFDM symbols 203 in a slot 206 may depend on the cyclicprefix length and subcarrier spacing.

FIG. 3 is a diagram depicting OFDM radio resources as per an aspect ofan embodiment of the present invention. The resource grid structure intime 304 and frequency 305 is illustrated in FIG. 3. The quantity ofdownlink subcarriers or RBs (in this example 6 to100 RBs) may depend, atleast in part, on the downlink transmission bandwidth 306 configured inthe cell. The smallest radio resource unit may be called a resourceelement (e.g. 301). Resource elements may be grouped into resourceblocks (e.g. 302). Resource blocks may be grouped into larger radioresources called Resource Block Groups (RBG) (e.g. 303). The transmittedsignal in slot 206 may be described by one or several resource grids ofa plurality of subcarriers and a plurality of OFDM symbols. Resourceblocks may be used to describe the mapping of certain physical channelsto resource elements. Other pre-defined groupings of physical resourceelements may be implemented in the system depending on the radiotechnology. For example, 24 subcarriers may be grouped as a radio blockfor a duration of 5 msec. In an illustrative example, a resource blockmay correspond to one slot in the time domain and 180 kHz in thefrequency domain (for 15 KHz subcarrier bandwidth and 12 subcarriers).

FIG. 5A, FIG. 5B, FIG. 5C and FIG. 5D are example diagrams for uplinkand downlink signal transmission as per an aspect of an embodiment ofthe present invention. FIG. 5A shows an example uplink physical channel.The baseband signal representing the physical uplink shared channel mayperform the following processes. These functions are illustrated asexamples and it is anticipated that other mechanisms may be implementedin various embodiments. The functions may comprise scrambling,modulation of scrambled bits to generate complex-valued symbols, mappingof the complex-valued modulation symbols onto one or severaltransmission layers, transform precoding to generate complex-valuedsymbols, precoding of the complex-valued symbols, mapping of precodedcomplex-valued symbols to resource elements, generation ofcomplex-valued time-domain DFTS-OFDM/SC-TDMA signal for each antennaport, and/or the like.

Example modulation and up-conversion to the carrier frequency of thecomplex-valued DFTS-OFDM/SC-TDMA baseband signal for each antenna portand/or the complex-valued PRACH baseband signal is shown in FIG. 5B.Filtering may be employed prior to transmission.

An example structure for Downlink Transmissions is shown in FIG. 5C. Thebaseband signal representing a downlink physical channel may perform thefollowing processes. These functions are illustrated as examples and itis anticipated that other mechanisms may be implemented in variousembodiments. The functions include scrambling of coded bits in each ofthe codewords to be transmitted on a physical channel; modulation ofscrambled bits to generate complex-valued modulation symbols; mapping ofthe complex-valued modulation symbols onto one or several transmissionlayers; precoding of the complex-valued modulation symbols on each layerfor transmission on the antenna ports; mapping of complex-valuedmodulation symbols for each antenna port to resource elements;generation of complex-valued time-domain OFDM signal for each antennaport, and/or the like.

Example modulation and up-conversion to the carrier frequency of thecomplex-valued OFDM baseband signal for each antenna port is shown inFIG. 5D. Filtering may be employed prior to transmission.

FIG. 4 is an example block diagram of a base station 401 and a wirelessdevice 406, as per an aspect of an embodiment of the present invention.A communication network 400 may include at least one base station 401and at least one wireless device 406. The base station 401 may includeat least one communication interface 402, at least one processor 403,and at least one set of program code instructions 405 stored innon-transitory memory 404 and executable by the at least one processor403. The wireless device 406 may include at least one communicationinterface 407, at least one processor 408, and at least one set ofprogram code instructions 410 stored in non-transitory memory 409 andexecutable by the at least one processor 408. Communication interface402 in base station 401 may be configured to engage in communicationwith communication interface 407 in wireless device 406 via acommunication path that includes at least one wireless link 411.Wireless link 411 may be a bi-directional link. Communication interface407 in wireless device 406 may also be configured to engage in acommunication with communication interface 402 in base station 401. Basestation 401 and wireless device 406 may be configured to send andreceive data over wireless link 411 using multiple frequency carriers.According to some of the various aspects of embodiments, transceiver(s)may be employed. A transceiver is a device that includes both atransmitter and receiver. Transceivers may be employed in devices suchas wireless devices, base stations, relay nodes, and/or the like.Example embodiments for radio technology implemented in communicationinterface 402, 407 and wireless link 411 are illustrated are FIG. 1,FIG. 2, FIG. 3, FIG. 5, and associated text.

An interface may be a hardware interface, a firmware interface, asoftware interface, and/or a combination thereof. The hardware interfacemay include connectors, wires, electronic devices such as drivers,amplifiers, and/or the like. A software interface may include codestored in a memory device to implement protocol(s), protocol layers,communication drivers, device drivers, combinations thereof, and/or thelike. A firmware interface may include a combination of embeddedhardware and code stored in and/or in communication with a memory deviceto implement connections, electronic device operations, protocol(s),protocol layers, communication drivers, device drivers, hardwareoperations, combinations thereof, and/or the like.

The term configured may relate to the capacity of a device whether thedevice is in an operational or non-operational state. Configured mayalso refer to specific settings in a device that effect the operationalcharacteristics of the device whether the device is in an operational ornon-operational state. In other words, the hardware, software, firmware,registers, memory values, and/or the like may be “configured” within adevice, whether the device is in an operational or nonoperational state,to provide the device with specific characteristics. Terms such as “acontrol message to cause in a device” may mean that a control messagehas parameters that may be used to configure specific characteristics inthe device, whether the device is in an operational or non-operationalstate.

According to some of the various aspects of embodiments, an LTE networkmay include a multitude of base stations, providing a user planePDCP/RLC/MAC/PHY and control plane (RRC) protocol terminations towardsthe wireless device. The base station(s) may be interconnected withother base station(s) (e.g. employing an X2 interface). The basestations may also be connected employing, for example, an S1 interfaceto an EPC. For example, the base stations may be interconnected to theMME employing the S1-MME interface and to the S-G) employing the S1-Uinterface. The S1 interface may support a many-to-many relation betweenMMEs/Serving Gateways and base stations. A base station may include manysectors for example: 1, 2, 3, 4, or 6 sectors. A base station mayinclude many cells, for example, ranging from 1 to 50 cells or more. Acell may be categorized, for example, as a primary cell or secondarycell. At RRC connection establishment/re-establishment/handover, oneserving cell may provide the NAS (non-access stratum) mobilityinformation (e.g. TAI), and at RRC connection re-establishment/handover,one serving cell may provide the security input. This cell may bereferred to as the Primary Cell (PCell). In the downlink, the carriercorresponding to the PCell may be the Downlink Primary Component Carrier(DL PCC), while in the uplink, it may be the Uplink Primary ComponentCarrier (UL PCC). Depending on wireless device capabilities, SecondaryCells (SCells) may be configured to form together with the PCell a setof serving cells. In the downlink, the carrier corresponding to an SCellmay be a Downlink Secondary Component Carrier (DL SCC), while in theuplink, it may be an Uplink Secondary Component Carrier (UL SCC). AnSCell may or may not have an uplink carrier.

A cell, comprising a downlink carrier and optionally an uplink carrier,may be assigned a physical cell ID and a cell index. A carrier (downlinkor uplink) may belong to only one cell. The cell ID or Cell index mayalso identify the downlink carrier or uplink carrier of the cell(depending on the context it is used). In the specification, cell ID maybe equally referred to a carrier ID, and cell index may be referred tocarrier index. In implementation, the physical cell ID or cell index maybe assigned to a cell. A cell ID may be determined using asynchronization signal transmitted on a downlink carrier. A cell indexmay be determined using RRC messages. For example, when thespecification refers to a first physical cell ID for a first downlinkcarrier, the specification may mean the first physical cell ID is for acell comprising the first downlink carrier. The same concept may applyto, for example, carrier activation. When the specification indicatesthat a first carrier is activated, the specification may equally meanthat the cell comprising the first carrier is activated.

Embodiments may be configured to operate as needed. The disclosedmechanism may be performed when certain criteria are met, for example,in a wireless device, a base station, a radio environment, a network, acombination of the above, and/or the like. Example criteria may bebased, at least in part, on for example, traffic load, initial systemset up, packet sizes, traffic characteristics, a combination of theabove, and/or the like. When the one or more criteria are met, variousexample embodiments may be applied. Therefore, it may be possible toimplement example embodiments that selectively implement disclosedprotocols.

A base station may communicate with a mix of wireless devices. Wirelessdevices may support multiple technologies, and/or multiple releases ofthe same technology. Wireless devices may have some specificcapability(ies) depending on its wireless device category and/orcapability(ies). A base station may comprise multiple sectors. When thisdisclosure refers to a base station communicating with a plurality ofwireless devices, this disclosure may refer to a subset of the totalwireless devices in a coverage area. This disclosure may refer to, forexample, a plurality of wireless devices of a given LTE release with agiven capability and in a given sector of the base station. Theplurality of wireless devices in this disclosure may refer to a selectedplurality of wireless devices, and/or a subset of total wireless devicesin a coverage area which perform according to disclosed methods, and/orthe like. There may be a plurality of wireless devices in a coveragearea that may not comply with the disclosed methods, for example,because those wireless devices perform based on older releases of LTEtechnology.

FIG. 6 and FIG. 7 are example diagrams for protocol structure with CAand DC as per an aspect of an embodiment of the present invention.E-UTRAN may support Dual Connectivity (DC) operation whereby a multipleRX/TX UE in RRC_CONNECTED may be configured to utilize radio resourcesprovided by two schedulers located in two eNBs connected via a non-idealbackhaul over the X2 interface. eNBs involved in DC for a certain UE mayassume two different roles: an eNB may either act as an MeNB or as anSeNB. In DC a UE may be connected to one MeNB and one SeNB. Mechanismsimplemented in DC may be extended to cover more than two eNBs. FIG. 7illustrates one example structure for the UE side MAC entities when aMaster Cell Group (MCG) and a Secondary Cell Group (SCG) are configured,and it may not restrict implementation. Media Broadcast MulticastService (MBMS) reception is not shown in this figure for simplicity.

In DC, the radio protocol architecture that a particular bearer uses maydepend on how the bearer is setup. Three alternatives may exist, an MCGbearer, an SCG bearer and a split bearer as shown in FIG. 6. RRC may belocated in MeNB and SRBs may be configured as a MCG bearer type and mayuse the radio resources of the MeNB. DC may also be described as havingat least one bearer configured to use radio resources provided by theSeNB. DC may or may not be configured/implemented in example embodimentsof the invention.

In the case of DC, the UE may be configured with two MAC entities: oneMAC entity for MeNB, and one MAC entity for SeNB. In DC, the configuredset of serving cells for a UE may comprise of two subsets: the MasterCell Group (MCG) containing the serving cells of the MeNB, and theSecondary Cell Group (SCG) containing the serving cells of the SeNB. Fora SCG, one or more of the following may be applied: at least one cell inthe SCG has a configured UL CC and one of them, named PSCell (or PCellof SCG, or sometimes called PCell), is configured with PUCCH resources;when the SCG is configured, there may be at least one SCG bearer or oneSplit bearer; upon detection of a physical layer problem or a randomaccess problem on a PSCell, or the maximum number of RLC retransmissionshas been reached associated with the SCG, or upon detection of an accessproblem on a PSCell during a SCG addition or a SCG change: a RRCconnection re-establishment procedure may not be triggered, ULtransmissions towards cells of the SCG are stopped, a MeNB may beinformed by the UE of a SCG failure type, for split bearer, the DL datatransfer over the MeNB is maintained; the RLC AM bearer may beconfigured for the split bearer; like PCell, PSCell may not bede-activated; PSCell may be changed with a SCG change (e.g. withsecurity key change and a RACH procedure); and/or neither a directbearer type change between a Split bearer and a SCG bearer norsimultaneous configuration of a SCG and a Split bearer are supported.

With respect to the interaction between a MeNB and a SeNB, one or moreof the following principles may be applied: the MeNB may maintain theRRM measurement configuration of the UE and may, (e.g, based on receivedmeasurement reports or traffic conditions or bearer types), decide toask a SeNB to provide additional resources (serving cells) for a UE;upon receiving a request from the MeNB, a SeNB may create a containerthat may result in the configuration of additional serving cells for theUE (or decide that it has no resource available to do so); for UEcapability coordination, the MeNB may provide (part of) the ASconfiguration and the UE capabilities to the SeNB; the MeNB and the SeNBmay exchange information about a UE configuration by employing of RRCcontainers (inter-node messages) carried in X2 messages; the SeNB mayinitiate a reconfiguration of its existing serving cells (e.g., PUCCHtowards the SeNB); the SeNB may decide which cell is the PSCell withinthe SCG; the MeNB may not change the content of the RRC configurationprovided by the SeNB; in the case of a SCG addition and a SCG SCelladdition, the MeNB may provide the latest measurement results for theSCG cell(s); both a MeNB and a SeNB may know the SFN and subframe offsetof each other by OAM, (e.g., for the purpose of DRX alignment andidentification of a measurement gap). In an example, when adding a newSCG SCell, dedicated RRC signalling may be used for sending requiredsystem information of the cell as for CA, except for the SFN acquiredfrom a MIB of the PSCell of a SCG.

In an example, serving cells may be grouped in a TA group (TAG). Servingcells in one TAG may use the same timing reference. For a given TAG,user equipment (UE) may use at least one downlink carrier as a timingreference. For a given TAG, a UE may synchronize uplink subframe andframe transmission timing of uplink carriers belonging to the same TAG.In an example, serving cells having an uplink to which the same TAapplies may correspond to serving cells hosted by the same receiver. AUE supporting multiple TAs may support two or more TA groups. One TAgroup may contain the PCell and may be called a primary TAG (pTAG). In amultiple TAG configuration, at least one TA group may not contain thePCell and may be called a secondary TAG (sTAG). In an example, carrierswithin the same TA group may use the same TA value and/or the sametiming reference. When DC is configured, cells belonging to a cell group(MCG or SCG) may be grouped into multiple TAGs including a pTAG and oneor more sTAGs.

FIG. 8 shows example TAG configurations as per an aspect of anembodiment of the present invention. In Example 1, pTAG comprises PCell,and an sTAG comprises SCell1. In Example 2, a pTAG comprises a PCell andSCell1, and an sTAG comprises SCell2 and SCell3. In Example 3, pTAGcomprises PCell and SCell1, and an sTAG1 includes SCell2 and SCell3, andsTAG2 comprises SCell4. Up to four TAGs may be supported in a cell group(MCG or SCG) and other example TAG configurations may also be provided.In various examples in this disclosure, example mechanisms are describedfor a pTAG and an sTAG. Some of the example mechanisms may be applied toconfigurations with multiple sTAGs.

In an example, an eNB may initiate an RA procedure via a PDCCH order foran activated SCell. This PDCCH order may be sent on a scheduling cell ofthis SCell. When cross carrier scheduling is configured for a cell, thescheduling cell may be different than the cell that is employed forpreamble transmission, and the PDCCH order may include an SCell index.At least a non-contention based RA procedure may be supported forSCell(s) assigned to sTAG(s).

FIG. 9 is an example message flow in a random access process in asecondary TAG as per an aspect of an embodiment of the presentinvention. An eNB transmits an activation command 600 to activate anSCell. A preamble 602 (Msg1) may be sent by a UE in response to a PDCCHorder 601 on an SCell belonging to an sTAG. In an example embodiment,preamble transmission for SCells may be controlled by the network usingPDCCH format 1A. Msg2 message 603 (RAR: random access response) inresponse to the preamble transmission on the SCell may be addressed toRA-RNTI in a PCell common search space (CSS). Uplink packets 604 may betransmitted on the SCell in which the preamble was transmitted.

According to some of the various aspects of embodiments, initial timingalignment may be achieved through a random access procedure. This mayinvolve a UE transmitting a random access preamble and an eNB respondingwith an initial TA command NTA (amount of timing advance) within arandom access response window. The start of the random access preamblemay be aligned with the start of a corresponding uplink subframe at theUE assuming NTA=0. The eNB may estimate the uplink timing from therandom access preamble transmitted by the UE. The TA command may bederived by the eNB based on the estimation of the difference between thedesired UL timing and the actual UL timing. The UE may determine theinitial uplink transmission timing relative to the correspondingdownlink of the sTAG on which the preamble is transmitted.

The mapping of a serving cell to a TAG may be configured by a servingeNB with RRC signaling. The mechanism for TAG configuration andreconfiguration may be based on RRC signaling. According to some of thevarious aspects of embodiments, when an eNB performs an SCell additionconfiguration, the related TAG configuration may be configured for theSCell. In an example embodiment, an eNB may modify the TAG configurationof an SCell by removing (releasing) the SCell and adding(configuring) anew SCell (with the same physical cell ID and frequency) with an updatedTAG ID. The new SCell with the updated TAG ID may initially be inactivesubsequent to being assigned the updated TAG ID. The eNB may activatethe updated new SCell and start scheduling packets on the activatedSCell. In an example implementation, it may not be possible to changethe TAG associated with an SCell, but rather, the SCell may need to beremoved and a new SCell may need to be added with another TAG. Forexample, if there is a need to move an SCell from an sTAG to a pTAG, atleast one RRC message, for example, at least one RRC reconfigurationmessage, may be send to the UE to reconfigure TAG configurations byreleasing the SCell and then configuring the SCell as a part of the pTAG(when an SCell is added/configured without a TAG index, the SCell may beexplicitly assigned to the pTAG). The PCell may not change its TA groupand may be a member of the pTAG.

The purpose of an RRC connection reconfiguration procedure may be tomodify an RRC connection, (e.g. to establish, modify and/or release RBs,to perform handover, to setup, modify, and/or release measurements, toadd, modify, and/or release SCells). If the received RRC ConnectionReconfiguration message includes the sCellToReleaseList, the UE mayperform an SCell release. If the received RRC Connection Reconfigurationmessage includes the sCellToAddModList, the UE may perform SCelladditions or modification.

In LTE Release-10 and Release-11 CA, a PUCCH is only transmitted on thePCell (PSCell) to an eNB. In LTE-Release 12 and earlier, a UE maytransmit PUCCH information on one cell (PCell or PSCell) to a given eNB.

As the number of CA capable UEs and also the number of aggregatedcarriers increase, the number of PUCCHs and also the PUCCH payload sizemay increase. Accommodating the PUCCH transmissions on the PCell maylead to a high PUCCH load on the PCell. A PUCCH on an SCell may beintroduced to offload the PUCCH resource from the PCell. More than onePUCCH may be configured for example, a PUCCH on a PCell and anotherPUCCH on an SCell. In the example embodiments, one, two or more cellsmay be configured with PUCCH resources for transmitting CSI/ACK/NACK toa base station. Cells may be grouped into multiple PUCCH groups, and oneor more cell within a group may be configured with a PUCCH. In anexample configuration, one SCell may belong to one PUCCH group. SCellswith a configured PUCCH transmitted to a base station may be called aPUCCH SCell, and a cell group with a common PUCCH resource transmittedto the same base station may be called a PUCCH group.

In an example embodiment, a MAC entity may have a configurable timertimeAlignmentTimer per TAG. The timeAlignmentTimer may be used tocontrol how long the MAC entity considers the Serving Cells belonging tothe associated TAG to be uplink time aligned. The MAC entity may, when aTiming Advance Command MAC control element is received, apply the TimingAdvance Command for the indicated TAG; start or restart thetimeAlignmentTimer associated with the indicated TAG. The MAC entitymay, when a Timing Advance Command is received in a Random AccessResponse message for a serving cell belonging to a TAG and/or if theRandom Access Preamble was not selected by the MAC entity, apply theTiming Advance Command for this TAG and start or restart thetimeAlignmentTimer associated with this TAG. Otherwise, if thetimeAlignmentTimer associated with this TAG is not running, the TimingAdvance Command for this TAG may be applied and the timeAlignmentTimerassociated with this TAG started. When the contention resolution isconsidered not successful, a timeAlignmentTimer associated with this TAGmay be stopped. Otherwise, the MAC entity may ignore the received TimingAdvance Command.

In example embodiments, a timer is running once it is started, until itis stopped or until it expires; otherwise it may not be running A timercan be started if it is not running or restarted if it is running. Forexample, a timer may be started or restarted from its initial value.

Example embodiments of the invention may enable operation ofmulti-carrier communications. Other example embodiments may comprise anon-transitory tangible computer readable media comprising instructionsexecutable by one or more processors to cause operation of multi-carriercommunications. Yet other example embodiments may comprise an article ofmanufacture that comprises a non-transitory tangible computer readablemachine-accessible medium having instructions encoded thereon forenabling programmable hardware to cause a device (e.g. wirelesscommunicator, UE, base station, etc.) to enable operation ofmulti-carrier communications. The device may include processors, memory,interfaces, and/or the like. Other example embodiments may comprisecommunication networks comprising devices such as base stations,wireless devices (or user equipment: UE), servers, switches, antennas,and/or the like.

The amount of data traffic carried over cellular networks is expected toincrease for many years to come. The number of users/devices isincreasing and each user/device accesses an increasing number andvariety of services, e.g. video delivery, large files, images. Thisrequires not only high capacity in the network, but also provisioningvery high data rates to meet customers' expectations on interactivityand responsiveness. More spectrum is therefore needed for cellularoperators to meet the increasing demand Considering user expectations ofhigh data rates along with seamless mobility, it is beneficial that morespectrum be made available for deploying macro cells as well as smallcells for cellular systems.

Striving to meet the market demands, there has been increasing interestfrom operators in deploying some complementary access utilizingunlicensed spectrum to meet the traffic growth. This is exemplified bythe large number of operator-deployed Wi-Fi networks and the 3GPPstandardization of LTE/WLAN interworking solutions. This interestindicates that unlicensed spectrum, when present, can be an effectivecomplement to licensed spectrum for cellular operators to helpaddressing the traffic explosion in some scenarios, such as hotspotareas. LAA offers an alternative for operators to make use of unlicensedspectrum while managing one radio network, thus offering newpossibilities for optimizing the network's efficiency.

In an example embodiment, Listen-before-talk (clear channel assessment)may be implemented for transmission in an LAA cell. In alisten-before-talk (LBT) procedure, equipment may apply a clear channelassessment (CCA) check before using the channel. For example, the CCAutilizes at least energy detection to determine the presence or absenceof other signals on a channel in order to determine if a channel isoccupied or clear, respectively. For example, European and Japaneseregulations mandate the usage of LBT in the unlicensed bands. Apart fromregulatory requirements, carrier sensing via LBT may be one way for fairsharing of the unlicensed spectrum.

In an example embodiment, discontinuous transmission on an unlicensedcarrier with limited maximum transmission duration may be enabled. Someof these functions may be supported by one or more signals to betransmitted from the beginning of a discontinuous LAA downlinktransmission Channel reservation may be enabled by the transmission ofsignals, by an LAA node, after gaining channel access via a successfulLBT operation, so that other nodes that receive the transmitted signalwith energy above a certain threshold sense the channel to be occupied.Functions that may need to be supported by one or more signals for LAAoperation with discontinuous downlink transmission may include one ormore of the following: detection of the LAA downlink transmission(including cell identification) by UEs; time & frequency synchronizationof UEs.

In an example embodiment, DL LAA design may employ subframe boundaryalignment according to LTE-A carrier aggregation timing relationshipsacross serving cells aggregated by CA. This may not imply that the eNBtransmissions can start only at the subframe boundary. LAA may supporttransmitting PDSCH when not all OFDM symbols are available fortransmission in a subframe according to LBT. Delivery of necessarycontrol information for the PDSCH may also be supported.

LBT procedure may be employed for fair and friendly coexistence of LAAwith other operators and technologies operating in unlicensed spectrum.LBT procedures on a node attempting to transmit on a carrier inunlicensed spectrum require the node to perform a clear channelassessment to determine if the channel is free for use. An LBT proceduremay involve at least energy detection to determine if the channel isbeing used. For example, regulatory requirements in some regions, e.g.,in Europe, specify an energy detection threshold such that if a nodereceives energy greater than this threshold, the node assumes that thechannel is not free. While nodes may follow such regulatoryrequirements, a node may optionally use a lower threshold for energydetection than that specified by regulatory requirements. In an example,LAA may employ a mechanism to adaptively change the energy detectionthreshold, e.g., LAA may employ a mechanism to adaptively lower theenergy detection threshold from an upper bound. Adaptation mechanism maynot preclude static or semi-static setting of the threshold. In anexample Category 4 LBT mechanism or other type of LBT mechanisms may beimplemented.

Various example LBT mechanisms may be implemented. In an example, forsome signals, in some implementation scenarios, in some situations,and/or in some frequencies no LBT procedure may performed by thetransmitting entity. In an example, Category 2 (e.g. LBT without randomback-off) may be implemented. The duration of time that the channel issensed to be idle before the transmitting entity transmits may bedeterministic. In an example, Category 3 (e.g. LBT with random back-offwith a contention window of fixed size) may be implemented. The LBTprocedure may have the following procedure as one of its components. Thetransmitting entity may draw a random number N within a contentionwindow. The size of the contention window may be specified by theminimum and maximum value of N. The size of the contention window may befixed. The random number N may be employed in the LBT procedure todetermine the duration of time that the channel is sensed to be idlebefore the transmitting entity transmits on the channel. In an example,Category 4 (e.g. LBT with random back-off with a contention window ofvariable size) may be implemented. The transmitting entity may draw arandom number N within a contention window. The size of contentionwindow may be specified by the minimum and maximum value of N. Thetransmitting entity may vary the size of the contention window whendrawing the random number N. The random number N is used in the LBTprocedure to determine the duration of time that the channel is sensedto be idle before the transmitting entity transmits on the channel.

LAA may employ uplink LBT at the UE. The UL LBT scheme may be differentfrom the DL LBT scheme (e.g. by using different LBT mechanisms orparameters) for example, since the LAA UL is based on scheduled accesswhich affects a UE's channel contention opportunities. Otherconsiderations motivating a different UL LBT scheme include, but are notlimited to, multiplexing of multiple UEs in a single subframe.

In an example, a DL transmission burst may be a continuous transmissionfrom a DL transmitting node with no transmission immediately before orafter from the same node on the same CC. An UL transmission burst from aUE perspective may be a continuous transmission from a UE with notransmission immediately before or after from the same UE on the sameCC. In an example, UL transmission burst is defined from a UEperspective. In an example, an UL transmission burst may be defined froman eNB perspective. In an example, in case of an eNB operating DL+UL LAAover the same unlicensed carrier, DL transmission burst(s) and ULtransmission burst(s) on LAA may be scheduled in a TDM manner over thesame unlicensed carrier. For example, an instant in time may be part ofa DL transmission burst or an UL transmission burst.

The following signals or combination of the following signals mayprovide functionality for the UE's time/frequency synchronization forthe reception of a DL transmission burst in LAA SCell(s): a) servingcell's DRS for RRM measurement (DRS for RRM measurement may be used atleast for coarse time/frequency synchronization), b) reference signalsembedded within DL transmission bursts (e.g. CRS and/or DMRS), and/or c)primary/secondary synchronization signals. If there is an additionalreference signal, this signal may be used. Reference signals may be usedat least for fine time/frequency synchronization. Other candidates(e.g., initial signal, DRS) may be employed for synchronization.

DRS for RRM may also support functionality for demodulation of potentialbroadcast data multiplexed with DRS transmission. Other mechanism orsignals (e.g., initial signal, DRS) for time/frequency synchronizationmay be needed to support reception of DL transmission burst.

In an example embodiment, DRS may be used at least for coarsetime/frequency synchronization. Reference signals (e.g., CRS and/orDMRS) within DL transmission bursts may be used at least for finetime/frequency synchronization. Once the UE detects DRS and achievescoarse time/frequency synchronization based on that, UE may keeptracking on the synchronization using reference signals embedded inother DL TX bursts and may also use DRS. In an example, a UE may utilizeDRS and/or reference signals embedded within DL transmission bursttargeting the UE. In another example, a UE may utilize DRS and/orreference signals embedded within many available DL transmission burstsfrom the serving cell (to the UE and other UEs).

The discovery signal used for cell discovery/RRM measurement (e.g.opportunistic transmission within configured DMTC) may be used formaintaining at least coarse synchronization with the LAA cell (e.g. <±3μs timing synchronization error and <±0.1 ppm frequency synchronizationerror). DRS may be subject to LBT. Inter-DRS latency generally getsworse as Wi-Fi traffic load increases. It is noted that the inter-DRSlatency can be rather significant. In example scenario, there may be 55%probability that the inter-DRS latency is 40 ms and there is 5%probability that inter-DRS latency is ≥440 ms. The inter-DRS latency asseen by the UE may be worse considering the possibility of misdetectionby the UE. Discovery signal misdetection may be due to actualmisdetection or due to UE unavailable for detection because of DRXinter-frequency measurement during DMTC occasion.

Depending on LAA DRS design, OFDM symbol boundary may be obtained byDRS. PCell and SCell timing difference may be kept, ±30 usec order. Theaggregated cells may be synchronized to some extent, e.g. aligned frametiming and SFN. Thus, similar requirement may be applied to the PCelland LAA cells on the unlicensed band. In an example, a UE may notutilize timing and frequency of the PCell for coarse synchronization ofLAA cells since the timing offset may be up to ˜30 us (e.g. non-located)and frequency reference may not be reliable due to the band distancebetween PCell and LAA cell (2 GHz Pcell and 5 GHz LAA cell). PCelltiming information also may be used for time synchronization at subframeor frame level. SCell(s) may employ the same frame number and subframenumber as the PCell.

PCell timing information may provide some information for symbolsynchronization. By synchronizing PCell, frequency difference observedby UE between PCell and LAA Scell may be up to 0.6 ppm. For example,after 300 ms, the amount of the time drift may be 0.18 usec at most. ForLAA, path delay may be relatively small as the target coverage is small.With timing drift, the multi-path delay may be within cyclic prefixlength.

According to some of the various aspects of embodiments, a UE mayutilize a licensed band carrier as a reference for time/frequencysynchronization for CA of licensed carrier and unlicensed carrier, forexample when they are in the same group (e.g. co-located). Whennon-collocated eNBs support licensed band PCell and unlicensed bandSCell separately in a CA scenario, there may exist maximum ˜30 us timingdifference between PCell and unlicensed band SCell. In an exampleembodiment, the frequency difference between the UE synchronized withPCell and unlicensed band SCell may observe at most 0.6 ppm. An LAA mayprovide functionality for time/frequency synchronization on unlicensedband at least for non-collocated CA scenario.

Example reasons of frequency difference may be 1) oscillator differenceamong PCell, SCell and UE, 2) Doppler shift and 3) fast fading aspect.The oscillator difference of 0.6 ppm offset in 5 GHz corresponds to 3kHz offset. Subcarrier spacing of LTE numerology is 15 kHz. This offsetmay need to be taken into account before FFT operation. One of thereasons of oscillator frequency variation is the temperature. If thefrequency difference is not obtained at the point of DRS reception, UEmay need to buffer subsequent data transmission until UE obtains thisfrequency difference before FFT. The frequency offset caused by this maybe obtained at the reception of DRS. Doppler shift may be small valuefor a low mobility UE. Fast fading and residual mismatch caused by 1)and 2) may be compensated during demodulation process similar to alicensed band. This may not require introducing additional referencesignals for unlicensed band.

According to some of the various aspects of embodiments, a UE may beconfigured to perform inter-frequency measurements on the carrierfrequency layer using measurement gaps for SCells that are notconfigured yet. SCell receiver may not be turned on and measurements maybe performed using the Pcell receiver. When a cell is added as Scell butnot activated (“deactivated state”), the UE may receive relevant systeminformation for the SCell from the Pcell. UE may be configured toperform measurements on the Scell without measurement gaps. SCellreceiver may need to be occasionally turned on (e.g. for 5 ms every 160ms) for RRM measurements using either CRS or Discovery signals. Cellsmay be added as Scell and activated (“activated state”), then the UE maybe ready to receive PDSCH on the Scell in all subframes. The SCellreceiver may perform (E)PDCCH monitoring in every subframe (for selfscheduling case). SCell receiver may buffer every subframe for potentialPDSCH processing (for both self and cross-carrier scheduling cases).

The eNodeB may configure the UE to measure and report RRM measurements(e.g. including RSSI) on a set of carrier frequencies. Once a suitablecarrier or a set of suitable carriers is determined, carrier selectedmay be added as an SCell by RRC (e.g. with ˜15 ms configuration delay),followed by SCell activation (with ˜24 ms delay). If an SCell isdeactivated, the UE may assume that no signal is transmitted by the LAAcell, except discovery signal may be transmitted when configured. If anSCell is activated, the UE is required to monitor PDCCH/EPDCCH andperform CSI measurement/reporting for the activated SCell. In a U-cell,a UE may not assume that every subframe of activated LAA SCell containstransmission. For LAA carriers, channel access may depend on the LBTprocedure outcome. The network may configure and activate many carriersfor the UE. The scheduler may then dynamically select carrier(s) for DLassignment or UL grant transmission.

According to some of the various aspects of embodiments, the first stageof cell level carrier selection may be during initial set up of a cellby an eNB. The eNB may scan and sense channels for interference or radardetection. eNB may configure the SCells accordingly based on the outcomeof its carrier selection algorithm for efficient load balancing andinterference management. The carrier selection process may be on adifferent time scale from the LBT/CCA procedure prior to transmissionson the carriers in unlicensed spectrum. The RSSI measurement report fromUE may be used to assist the selection at eNB.

According to some of the various aspects of embodiments, the secondstage of cell level carrier selection is after initial set up. Themotivation is that eNB may need to do carrier (re)selection due tostatic load and interference change on some carriers, e.g., a new Wi-FiAP is set up and continuously accesses the carrier causing relativelystatic interference. Therefore, semi-static carrier selection may bebased on the eNB sensing of the averaged interference level, potentialpresence of radar signals if required, and traffic load on the carriersover a relatively longer time scale, as well as RRM measurement from UEsin the cell. Due to the characteristics in unlicensed spectrum, RRMmeasurements on LAA SCells may be enhanced to support better carrierselection. For example, the RSSI measurement may be enhanced usingoccupancy metric indicating the percentage of the time when RSSI isabove a certain threshold. It may be noted that cell level carrierselection may be a long-term (re)selection since the process may berather costly due to the signalling overhead and communicationinterruptions for UEs in a cell and it may also affect the neighbouringcells. Once a suitable set of carriers is identified, they may beconfigured and activated as SCells for UEs. This process may becontinuous in order to keep reassessing the interference environment.Cell-level carrier selection in unlicensed spectrum may be a relativelylong-term (re)selection based on eNB sensing and RRM measurement reportfrom UE. RRM measurement on LAA SCells may be enhanced to support bettercarrier selection.

Carrier selection from UE perspective may be to support carrierselection for a UE among the set of carriers that the eNB has selectedat the cell level. Carrier selection for the UE in unlicensed spectrummay be achieved by configuring a set of the carriers on which the UEsupports simultaneous reception and transmission. The UE may perform RRMmeasurements on the configured carriers and report them to the eNB. TheeNB may then choose which of the carriers to activate and use fortransmission when it has pending data for the UE. The number of carriersto activate may then also be chosen based on the data rate needed andthe RRM measurements for the different carriers. The activation delayfor a carrier before scheduling data on it may be up to ˜24 ms, assumingthat the UE has performed RRM measurement on this carrier prior toreceiving the activation command within DRX cycle. By operating thecarrier selection based on activation and deactivation, the selectionmay also be done in the order of tens of ms.

According to some of the various aspects of embodiments, CRS may not betransmitted in an activated subframe when a burst is not scheduled inthat subframe. If there are no transmissions from the eNB for anextended duration (Toff), UE demodulation performance may be impacteddue to lack of reference symbols for fine time/frequency tracking. Theextent of performance impact depends on the amount of time for whichthere are no eNB transmissions. The impact may be mitigated by morefrequent transmission of discovery signals.

Discovery signals may be transmitted by the eNB even when UEs are notbeing scheduled. Setting discovery signal periodicity based on UE RRMmeasurement requirements (e.g. 160 ms) may be more efficient thansetting the periodicity based on UE fine time/frequency trackingrequirement.

In an example embodiment, Scell deactivation timer for the unlicensedScell may be set to a value closer to (Toff) based on UE finetime/frequency tracking requirements. This may result in more frequenttransmission of activation commands Activation commands may be neededwhen the eNB has data to schedule to a UE. From the UE perspective,after receiving an activation command in a particular subframe, the UEmay receive CRS in a number (e.g. one or two) of following subframes.The UEs may receive CRS transmissions for a few symbols or subframes,which they may use for settling AGC loop and time-frequency trackingfilters before PDSCH reception on the SCell. UEs may receive CRStransmission (e.g. in a few OFDM symbols) between reception ofactivation command and reception PDSCH on the Scell.

Activating a large number of carriers on dynamic bases may increase theUE power consumption, false alarm probability, and processing powerrequirements. Improved mechanisms are needed to improve efficiency inthe UE and enable fast and dynamic carrier selection/activation in a UE.Novel mechanisms may reduce UE power consumption, reduce false alarmprobability and reduce processing power requirements. Carrier selectionand activation may be enhanced to achieve fast dynamic carrier selection(or switching). A fast activation procedure for the carrier (e.g.shorter than the currently defined 24 ms) may be defined to improveefficiency.

Current SCell activation latency may include the MAC CE decoding latency(˜3-6 ms) and SCell activation preparation time (RF preparation, up to˜18 ms). Implementation of faster processes and hardware may reducethese delays. SCell MAC activation/deactivation signalling isUE-specific. Signalling overhead may be a concern especially if the cellused for transmitting the signal is a macro cell. In an exampleembodiment, a L1 procedure/indicator may be introduced and/or SCellactivation signalling may be enhanced.

Layer one signalling (e.g. PDCCH/EPDCCH from the PCell or anotherserving cell) may be implemented to signal the set of carriers that theUE may monitor for PDCCH/EPDCCH and/or measuring/reporting CSI. Controlsignalling latency may be ˜2 ms (e.g. one 1 ms EPDCCH transmission plus0.5 ms decoding). The DCI format may be of small size for transmissionreliability and overhead reduction. To reduce control signallingoverhead, the signalling may be a UE-common signalling. The indicationmay be sent on a carrier that the UE is currently monitoring.

In an example embodiment, a mechanism based on a L1 indication forstarting/stopping monitoring of up to k activated carriers may beprovided. The UE may be configured with n>=k CCs. k CCs may be activatedvia MAC signalling of SCell activation/deactivation. Then based on LBTprogress over the CCs, a L1 indication is sent to inform which of the kCCs may be monitored by the UE and which may not. The UE may thenreceive data burst(s) on the monitored CCs. Another L1 indication may besent after the bursts to alter which CCs may be monitored since then,and so on. The L1 indication may be explicit (e.g., based on asignalling) or implicit (e.g., based on self scheduling and UE detectionof scheduling information on the SCell). For this example, fast carrierswitching is done among at most k CCs.

In an example embodiment, a mechanism based on a L1 signalling forstarting/stopping monitoring of up to m activated carriers (the numberof p configured carriers may be m or higher). The activated carriers maybe more than n (e.g., there may be more CCs activated for the UE thanits PDSCH aggregation capability-n). The UE is configured with p CCs,and there may be up to m CCs that are activated via MAC signalling ofSCell activation/deactivation. The UE may not monitor all the activatedCCs. The UE may monitor at most n CCs according a L1 indication. The L1indication needs to be explicit rather than implicit, since an implicitindication may require a UE to monitor all the up to m activatedcarriers at the same time, exceeding the UE's capability. For thisexample, fast carrier switching is done among possibly more than n CCs.

According to some of the various aspects of embodiments, SCellactivation/deactivation enhancements may be considered for fast carrierswitching. SCell activation/deactivation signalling is a MAC signalling.MAC signalling decoding/detection (with or without enhancements) may beslower than L1 signalling decoding/detection. It may involvesdecoding/detection of a L1 signalling and furthermore, a PDSCH. If SCellactivation/deactivation is carried by a L1 signalling, it may still beconsidered for fast carrier switching. In an example embodiment, amechanism based on a L1 signalling for activation/deactivation of the pconfigured carriers. The UE is configured with p CCs, but each timethere are at most n CCs are activated via a L1 signalling of SCellactivation/deactivation. For instance, based on LBT progress over theCCs, a L1 signalling is sent to inform which of the p CCs are activated.The UE may receive data burst(s) on the activated CCs. Another L1signalling may be sent after the bursts to alter the activated CCs. Forthis example, fast carrier switching is done among possibly more than nCCs.

The control signalling may be transmitted before the eNB has gainedaccess to the carrier via LBT process. An eNB may inform the UE to start(or stop) monitoring a carrier (whether the UE would receive a burst ornot depends on the presence of PDCCH scheduling information for thecarrier). An indication for starting monitoring may be used for morethan one burst, until an indication for stopping monitoring is sent. Theindication may be sent when the eNB expects the (E) CCA is to completesoon. A purpose of the indication may be to inform a UE to start or stopmonitoring a carrier.

Transmitting the control signalling after the eNB has gained access tothe carrier may incur overhead of the reservation signal (proportionalto the control signalling latency). In an example, the maximumtransmission burst may be 4 ms. An eNB may inform the UE to receive aburst on a carrier. The eNB may send one indication for a burst. Theremay be many short bursts (e.g., one burst may last up to 4 millisecondsin certain regions). The indication may be sent after (E)CCA iscompleted, consuming some portion of the maximum allowed transmissionduration for a burst.

It may still be up to the network to transmit the control signallingbefore or after the channel is occupied. A UE may detect that the burstis from the serving cell (e.g. by confirming PCID). The function of thecontrol signalling is to indicate that the UE may perform DLtransmission burst detection of the serving cell. If a DL burst of theserving cell is detected, UE may monitor for possible PDCCH/EPDCCHand/or measuring the CSI on the indicated SCell.

In an example embodiment, a UE may be configured with a number ofcarriers potentially exceeding the maximum number of carriers over whichthe UE may aggregate PDSCH. RRM measurements over the configuredcarriers may be supported, e.g. RSSI-like measurement, extension ofquasi co-location concept to across collocated intra-band carriers,and/or carrier grouping. L1 indication to the UE to start monitoring acarrier, which is selected from the configured carriers by the eNB maybe supported.

According to some of the various aspects of embodiments, an eNB mayconfigure UE with more component carriers which may potentially exceedthe maximum number of carriers over which the UE may aggregate PDSCH.Then eNB may activate one or more carriers among the configured carriersto UE by the existing signalling, e.g. MAC signalling. UE may bescheduled on the one or more activated carriers dynamically based on theLBT mechanism.

A UE may switch to receive on any carrier within a set of carriersselected by the serving eNB as fast as subframe/symbol-level, while thenumber of carriers within the set may potentially exceed the maximumnumber of carriers over which the UE may aggregate PDSCH. Whichcarrier(s) the UE may switch to is per eNB indication. When the UE isindicated with the carrier(s) it may switch to, the UE may start tomonitor the indicated carrier(s), e.g. within a few subframes, and maystop monitoring other carriers. By monitoring a carrier it meant tobuffer and attempt to detect the control channels and other associatedchannels. The eNB indication may instruct the UE to switch to theindicated carrier(s) and monitor the carrier(s). The eNB may notinstruct the UE to switch to monitor on more carriers than its PDSCHaggregation capability in a given subframe. The eNB may not schedule theUE on more carriers than its PDSCH aggregation capability. SCellconfiguration enhancements may allow both semi-static and fast carrierswitching with reduced transition time. The delay associated with theSCell configuration signalling as well as the delay associated with themeasurement process may be decreased.

In an example embodiment, fast carrier switching may support UE toswitch to any carrier within a set of carriers selected by the servingeNB as fast as a few subframes/symbols. The eNB may send an indicationinstructing the UE to switch to the indicated carriers and monitor thecarriers. Then the UE may perform the switching and start monitoring theindicated carriers. The UE stops monitoring other carriers. The eNBindication may be done in L1. A L1 procedure/indicator, or anenhancements of the SCell activation signalling may be introduced.

According to some of the various aspects of embodiments, DRS design mayallow DRS transmission on an LAA SCell to be subject to LBT. Thetransmission of DRS within a DMTC window if LBT is applied to DRS mayconsider many factors. Subjected to LBT, DRS may transmitted in fixedtime position within the configured DMTC. Subject to LBT, DRS may betransmitted in at least one of different time positions within theconfigured DMTC. The number of different time positions may berestricted. One possibility is one time position in the subframe. DRStransmissions outside of the configured DMTC may be supported.

According to some of the various aspects of embodiments, an sensinginterval may allow the start of a DL transmission burst (which may notstart with the DRS) containing DRS without PDSCH within the DMTC. Totalsensing period may be greater than one sensing interval. Whether theabove may be used for the case where transmission burst may not containPDSCH but contains DRS, and any other reference signals or channels. TheECCA counter used for LBT category 4 for the PDSCH may be frozen duringDL transmission burst containing DRS without PDSCH

The RS bandwidth and density/pattern of the DRS design for LAA maysupport for RRM measurement based on a single DRS occasion.

According to some of the various aspects of embodiments, Discoverysignal may be transmitted via a successful LBT operation. When the eNBdoes not have access to the channel, the discovery signal burst may notbe transmitted. In an example, the discovery signal periodicity isconfigured to be 40 ms, and it may be possible to receive the discoverysignal at least once in every 160 to 200 ms with a high probability. Forexample, the probability of receiving a discovery signal burst at leastonce in every 160 ms may greater than 97%. The UE may adjust itsreceiver processing to account for the potential absence of discoverysignals due to lack of access to the channel. For instance, the UE maydetect the presence or absence of a particular discovery signal burstusing the PSS, SSS and CRS signals.

According to some of the various aspects of embodiments, the use ofdiscovery signals that may be subject to LBT. A discovery signal burstmay not be transmitted when LBT fails. Data may be transmitted in theintervening subframes. The reference signals along with controlinformation may be used to reserve the channel prior to a discoverysignal or data transmission.

For reception of data on the serving cell, AGC and fine time andfrequency estimation may employ the discovery signals from the servingcell. In an example, time and frequency estimation may be performedusing the PSS, SSS and/or CRS inside the discovery signal subframes. Theuse of two or more CRS ports may enhance synchronization performance.These signals may provide synchronization estimates that are adequatefor the purpose of RRM measurements on the serving and neighboringcells. When data is to be received by the UE in a subframe that occurs asignificant number of subframes after the last reception of a discoverysignal on the serving cell. Fine tuning of the time and frequencyestimates may be performed using the DM-RS and, if present, the CRSwithin the subframe in which data is received, and/or the initialsignal. The signal used to reserve the channel before the actual startof data transmissions (e.g. reservation signal, initial signal, and/orburst indicator) may be used to fine tune time and frequency estimatesbefore the reception of data. When transmitting data after a longabsence of any discovery signal or other transmissions, the eNB maytransmit a signal of longer duration to reserve the channel in order tofacilitate the use of such a signal for timing and frequencyadjustments.

CRS may not be transmitted in an activated subframe when a burst is notscheduled in that subframe. If there are no transmissions from the eNBfor an extended duration (Toff), UE demodulation performance may beimpacted due to lack of reference symbols for fine time/frequencytracking. The extent of performance impact depends on the amount of timefor which there are no eNB transmissions. The impact may be mitigated bymore frequent transmission of discovery signals.

Discovery signals may be transmitted by the eNB even when UEs are notbeing scheduled. Setting discovery signal periodicity based on UE RRMmeasurement requirements (e.g. 160 ms) may be more efficient thansetting the periodicity based on UE fine time/frequency trackingrequirement.

DRS design may allow DRS transmission on an LAA SCell to be subject toLBT. The transmission of DRS within a DMTC window if LBT is applied toDRS may consider many factors. Subjected to LBT, DRS may be transmittedin fixed time position within the configured DMTC. Subject to LBT, DRSmay be transmitted in at least one of different time positions withinthe configured DMTC. The number of different time positions may berestricted. One possibility is one time position in the subframe.

The following signals or combination of the following signals mayprovide functionality for the UE's time/frequency synchronization forthe reception of a DL transmission burst in LAA SCell(s): serving cell'sDRS for RRM measurement, DRS for RRM measurement may be used at leastfor coarse time/frequency synchronization. Reference signals may beimbedded within DL transmission bursts (e.g. CRS and/or DMRS). If thereis an additional reference signal, this signal may be used. Referencesignals may be used at least for fine time/frequency synchronization.Other candidate signals (e.g., initial signal, DRS) may be considered.

DRS for RRM may also support functionality for demodulation of potentialbroadcast data multiplexed with DRS transmission. Broadcast datatransmission with DRS may be supported. Other mechanism or signals(e.g., initial signal, DRS) for time/frequency synchronization maysupport reception of DL transmission burst

Discovery signal may be transmitted via a successful LBT operation. Whenthe eNB does not have access to the channel, the discovery signal burstmay not be transmitted. In an example, the discovery signal periodicityis configured to be 40 ms, and it may be possible to receive thediscovery signal at least once in every 160 to 200 ms with a highprobability. For example, the probability of receiving a discoverysignal burst at least once in every 160 ms may greater than 97%. The UEmay adjust its receiver processing to account for the potential absenceof discovery signals due to lack of access to the channel. For instance,the UE may detect the presence or absence of a particular discoverysignal burst using the PSS, SSS and CRS signals. The use of discoverysignals that may be subject to LBT. A discovery signal burst may not betransmitted when LBT fails.

For reception of data on the serving cell, AGC and fine time andfrequency estimation may employ the discovery signals from the servingcell. Time and frequency estimation may be performed using the PSS, SSSand/or CRS inside the discovery signal subframes. The use of two or moreCRS ports may enhance synchronization performance. These signals mayprovide synchronization estimates that are adequate for the purpose ofRRM measurements on the serving and neighbouring cells. When data is tobe received by the UE in a subframe that occurs a significant number ofsubframes after the last reception of a discovery signal on the servingcell. Fine tuning of the time and frequency estimates may be performedusing the DM-RS and, if present, the CRS within the subframe in whichdata is received, and/or the initial signal. The signal used to reservethe channel before the actual start of data transmissions (e.g.reservation signal, initial signal, and/or burst indicator) may be usedto fine tune time and frequency estimates before the reception of data.

In legacy LTE technology, if the MAC entity receives anActivation/Deactivation MAC control element in a TTI activating theSCell, the MAC entity may: activate the SCell; e.g. apply normal SCelloperation including: SRS transmissions on the SCell; CQI/PMI/RI/PTIreporting for the SCell; PDCCH monitoring on the SCell; PDCCH monitoringfor the SCell. The MAC entity may start or restart thesCellDeactivationTimer associated with the SCell. The MAC entity maytrigger PHR if the cell is configured with an uplink.

For Rel-12 and before, the UE expects to receive signals from the SCellwhen it activates an SCell. The UE receives signals such as CRS, CSI-RS,PSS, SSS that are transmitted in the SCell throughout the activatedduration. The UE may perform (e)PDCCH monitoring and CSI measurementcontinuously, due to contiguous transmission. When the SCell isdeactivated, the UE may not assume that there is transmission from theSCell other than discovery signal if DRS is configured.

In an unlicensed (e.g. LAA) cell, when the cell is activated, a UE maystart performing the activation tasks including SRS transmissions on theSCell; CQI/PMI/RI/PTI reporting for the SCell; PDCCH monitoring on theSCell; PDCCH monitoring for the SCell. The MAC entity may start orrestart the sCellDeactivationTimer associated with the SCell. The MACentity may trigger PHR if the cell is configured with an uplink. Unlikein licensed cells, a UE may not need to perform PDCCH monitoring and CSImeasurement continuously for an LAA cell. A UE may perform PDCCHmonitoring when PDCCH is transmitted. A UE may perform CSI measurementwhen CSI-RS and/or CRS signals are transmitted. A UE may not performPDCCH monitoring and CSI measurement when these signals are nottransmitted. A UE may perform blind detection on whether SCell istransmitting CSI-RS (or a similar signal, e.g. DRS, CRS, SS, etc). Ifthe UE determines the activated SCell is transmitting CSI signal, the UEmay measure and transmit CSI measurement to the eNB via PUCCH and/orPUSCH. If the UE determines the activated SCell is transmitting (e)PDCCHsignal, the UE may monitor (e)PDCCH for the received DCIs.

A separate mechanism may be needed for the UE to determine that theactivated LAA SCell is actually transmitting a signal. The correspondingcell operation may be performed for that signal (e.g. PDCCH/EPDCCHmonitoring, CSI measurement and reporting) if the signal is transmitted.

In an example embodiment, when an unlicensed cell is activated in a UEby an eNB, the UE may need to detect the presence of the (e)PDCCHchannel, if a UE implicitly or explicitly determines that (e)PDCCH istransmitted, the UE may monitor the channel. The UE may detect thepresence of the PDCCH signal by blind decoding the physical signals onthe unlicensed cell.

For example, the blind decoding may be based on detection of whether CRSpower in a given subframe/symbol is above some certain threshold. Ablind detection may detect that the CRS is transmitted, and if CRS istransmitted the UE may monitor PDCCH. In another example, the UE mayblind decode the CRS signal, or SS transmission (e.g. in subframes 0 and5), and/or CSI-RS in subframes that CSI-RS is configured. In an exampleembodiment, when a LAA cell is activated, the UE may blind decode forthe presence of a PCFICH, the UE may implement blind decoding forphysical signals (PCFICH, CRS, SS, etc) to detect whether PDCCH istransmitted and whether PDCCH should be monitored. In an exampleembodiment, an indicator signal may be transmitted in every subframe inwhich (e)PDCCH is transmitted indicating the presence of the (e)PDCCH. AUE may blind decode the indicator signal to determine whether (e)PDCCHis transmitted. The indicator signal may be a known signal or have aknown pattern or be selected from a set of known signals. For example,an indicator may be a combination of at least one of CSI-RS, CRS, PSS,SSS, DMRS, and/or the like.

When an SCell is activated, the UE may measure and transmit CSI duringthe downlink burst transmission. When there is no downlink burst (databurst) transmission, CSI (or any other signal suitable for CSImeasurement, e.g. DRS, CRS, etc) may or may not be transmitted during asubframe configured for CSI. Signal transmissions including DRStransmission is subject to LBT, and an eNB may not be able to transmitthe CSI-RS signal due to a busy channel. In an example implementation,an eNB may selectively decide not to transmit CSI-RS in a configuredsubframe, to reduce interference to other cells. A UE may not assumeCSI-RS is always transmitted in a configured CSI-RS subframe/symbol.When CSI-RS is configured for a LAA cell, the UE may first need todetermine whether CSI-RS is transmitted, and if CSI-RS is transmittedthe UE may measure the CSI-RS and report the CSI to the eNB. This isunlike legacy LTE-A technology, wherein a UE assumes that CSI-RS istransmitted in a configured CSI subframe/symbol/subcarrier. In anunlicensed (e.g. LAA) cell, CSI-RS may be transmitted in CSI-RSconfigured subframes during a downlink transmission burst.

CSI measurement by a UE when no downlink data burst is transmittedrequires further improvement. When DRS is transmitted, DRS may betransmitted on an unlicensed cell, when the unlicensed cell isdeactivated or activated for a UE. In an example embodiment, for anactivated unlicensed cell, a UE may measure CSI when DRS is transmitted.

An eNB may transmit CSI-RS along with other signals (such as CRS, SS, oranother other newly defined signal) to enable and/or support CSI-RSdetection and measurement. For example, DRS may be used to measure CSIfor an activated LAA cell. When an unlicensed cell (e.g. LAA cell) isactivated, a UE first need to determine CSI-RS (or e.g. DRS) istransmitted. In an example implementation, the presence of themeasurement signal (e.g. CSI-RS, DRS) may be detected by blind decodingin a subset of subframes employing the information about the DRS and/orCSI-RS configuration. When there is no downlink transmission data burst,the presence of the measurement signal (e.g. CSI-RS, DRS, etc) may bedetected by blind decoding.

When LAA cell is activated, the UE may first detect the presence of themeasurement signal, and then measure the measurement signal. The UE maytransmit the measured CSI in the first PUCCH opportunity (UCI) for CSItransmission (or via PUSCH TB piggy backing). In legacy LTE, the UE maymeasure CSI-RS in any subframe that CSI-RS is configured, and UE maytransmit OOR signal if the measurement is unsuccessful or themeasurement indicates an out of range (OOR) value.

When UE receives an activation command in subframe n to activate anSCell, the UE may start activation timer at n+k and start CSItransmission at n+k (e.g. k=8). The UE may initially transmit OOR CSI,until it successfully measures a valid CSI. Then the UE startstransmitting valid CSI based on UE measurements. After an eNB activatedan SCell by transmitting an activation command, the eNB may initiallyreceives OOR CSI values for the SCell from the UE (if valid CSI is notavailable) and then the eNB may receive valid CSI values. If the UE isable to activate the SCell quickly and if the UE was able to measure avalid CSI before the first available CSI transmission opportunity on orafter n+k, the UE may transmit a valid CSI and may not transmit an OORCSI. In a licensed cell, CSI RS is transmitted on an activated SCell andis received by a UE in the configured subframe/symbol/subcarriers,regardless of whether PDSCH signals are transmitted or not. In an LAAcell, CSI RS signals are transmitted as a part of DRS signal, or CSI RSsignals are transmitted in CRS-RS configured subframe during a downlinktransmission burst when PDSCH is transmitted.

In an example embodiment of the invention, if the MAC entity isconfigured with one or more SCells, the network may activate anddeactivate the configured SCells. The SpCell may always be activated.The network may activate and deactivate the SCell(s) by sending theActivation/Deactivation MAC control element. The MAC entity may maintaina sCellDeactivationTimer timer per configured SCell. The same initialtimer value may apply to an instance of the sCellDeactivationTimer andsCellDeactivationTimer is configured by RRC. The configured SCells maybe initially deactivated upon addition and after a handover. In anexample embodiment, unlicensed cells (e.g. LAA cells) and licensed cellsmay be configured with the same or different deactivation timer value.

When the MAC layer determines that a secondary cell is deactivated oractivated in a subframe, there may be a delay between the subframe whenthe determination was made and when the steps for deactivation oractivation of the secondary cell takes place. When MAC layer deactivatesor activates a secondary cell in a subframe (e.g. due to receiving a MACActivation/Deactivation Command), the related actions may be taken aftera certain delay (e.g. processing delay, hardware, etc). The delay maydepend on UE and eNB implementation and may be specified in the standardor preconfigured in the system. In an example embodiment, when a UEreceives an activation command for a secondary cell in subframe n, thecorresponding actions in the MAC layer may be applied no later than aminimum requirement (e.g. no later than a maximum activation delay interms or subframes or ms) and no earlier than subframe n+8, except forthe following: the actions related to CSI reporting; and the actionsrelated to the sCellDeactivationTimer associated with the secondary cellwhich may be applied in subframe n+8.

In an example embodiment, when a UE receives a deactivation command fora secondary cell or the sCellDeactivationTimer associated with thesecondary cell expires in subframe n, the corresponding actions mayapply no later than the minimum requirement (e.g. no later than amaximum deactivation delay), except for the actions related to CSIreporting which may be applied in subframe n+8.

In an example embodiment, a UE may transmit a UE capability message tothe eNB. The UE capability message may be transmitted to the eNB inresponse to a request message received from the eNB. In an exampleembodiment, one or more parameters in the UE capability message mayindicate that the UE supports configuration of a plurality of cellscomprising licensed cells and unlicensed (e.g. LAA) cells.

In an example embodiment, one or more parameters in the UE capabilitymessage may implicitly or explicitly indicate that the UE may differentmaximum activation delay requirements for different types of cells. Thecapability indication may be implicit. For example, the one or moreparameters in the capability message may indicate support for downlinkLAA cells. The presence of the one or more parameters may indicate thatthe UE may support downlink LAA operation. Downlink LAA operation mayinclude activation/deactivation of LAA cells, identification of downlinktransmissions on LAA cell(s) for full downlink subframes, decoding ofcommon downlink control signalling on LAA cell(s), CSI feedback for LAAcell(s), RRM measurements on LAA cell(s) based on CRS-based DRS, and/orthe like. In an example, activation delay requirements for an unlicensedcell may indicate a faster activation delay for LAA cells. In anexample, the activation delay may be faster for a certain cell type(compared with R-12 requirements). In an example, the activation delayrequirements may be different for a licensed cell compared with anunlicensed (e.g. LAA) cell.

An eNB may transmit to the UE an RRC message comprising configurationparameters of a plurality of cells comprising one or more licensed cellsand one or more unlicensed (e.g. LAA) cells.

In an example, a UE may receive an activation command comprising one ormore fields (parameters) instructing the UE to activate one or morelicensed cell and one or more unlicensed cells. In an example, a UE mayreceive a first activation command comprising one or more first fields(parameters) instructing the UE to activate one or more licensed cell.The UE may receive a second activation command comprising one or moresecond fields (parameters) instructing the UE to activate one or moreunlicensed cells. The order in which an eNB transmits activationcommand(s) to activate secondary cell(s) is up to eNB implementation andmay depend on the traffic and channel conditions.

When the UE receives a MAC CE instructing the UE to activate a LAA cell,the UE may be capable to transmit valid CSI report and apply actionsrelated to the activation command for the LAA cell being activated nolater a first maximum number of subframes. When the UE receives a MAC CEinstructing the UE to activate a licensed cell, the UE may be capable totransmit valid CSI report and apply actions related to the activationcommand for the licensed cell being activated no later a second maximumnumber of subframes. The first maximum number of subframes may bedifferent than the second maximum number of subframes.

Discovery signal may be transmitted via a successful LBT operation. Whenthe eNB does not have access to the channel, the discovery signal burstmay not be transmitted. When a UE receives a MAC CE instructing the UEto activate an LAA cell, the UE may employ DRS signal on the LAA cellfor synchronization and/or measurements. The first maximum number ofsubframes (maximum activation delay) for an LAA cell may depend on thenumber of times the discovery signal occasion is not available at the UEduring the LAA cell activation time. When discovery signal is nottransmitted one or more times, the first maximum number of subframes maybe increased.

Implementing the same maximum number of subframes for activation delayfor different cell types may delay activation delay in a UE and/or eNB.When LAA cells are introduced, different cell types may requiredifferent types of signals and may require the UE/eNB to performdifferent processes before performing actions related to the activation.When the same maximum number of subframes is used for various cell typesby the eNB/UE, then the eNB/UE may need to set the value of the maximumnumber of subframes to a larger number. This may result in a longeractivation delay. The eNB may need to wait longer before the eNB canschedule downlink and/or uplink TBs and/or signals for the cell aftertransmitting the activation command for the cell. The exampleembodiments improve activation delay for a UE and/or eNB.

In an example embodiment, the activation delay requirements may dependon cell type. For example, unlicensed (e.g. LAA) cells may have ashorter activation delay compared with the licensed cells. For example,activation requirement for a licensed cell may follow legacyrequirements. Activation timer and CSI transmission may start after 8subframes. Other activities such as PDCCH monitoring may take longer(e.g. 24 msec) depending on the state of the UE when it receives theactivation command. An eNB may receive OOR CSI from the UE until the UEis able to measure and transmit valid CSIs to the eNB. Activation delayfor unlicensed (e.g. LAA) cells may be different. In an example, some ofthe activities such as PDCCH monitoring for a newly activated LAA cellmay take less time compared with a licensed cell (e.g. 12 msec)depending on the state of the UE. In an example, an eNB may be able tostart downlink transmission on a LAA cell earlier compared with downlinktransmission on a licensed cell.

In an example embodiment, an eNB may transmit an RRC message comprisingconfiguration parameters about a plurality of cells. The plurality ofconfiguration parameters may determine (implicitly or explicitly) theactivation delay of a configured SCell. For example, the configurationparameters may define a cell type, which may determine the activationdelay requirements of that cell type. In an example, configurationparameters may define an activation delay requirement or an activationtimer value, which may determine the activation delay for a configuredcell.

In an example embodiment, the delay within which a UE may be able toactivate a deactivated LAA cell may depend upon the UE conditions. Uponreceiving SCell activation command in subframe n, the UE may be able totransmit valid CSI report and apply actions related to the activationcommand for the SCell being activated no later than in n+a first maximumnumber of subframes. In an example, when a different set of conditionsare met for the SCell, then a different first maximum number ofsubframes may be employed. In an example, the first maximum number ofsubframes may be defined for a scenario in which some conditions are metfor the SCell. The first maximum number of subframes may also depend onthe number detection attempts needed to detect the cell. The firstmaximum number of subframes may be a sum of various parameters, e.g. afixed pre-specified number, the periodicity of the DMTC, and/or thenumber of times the discovery signal occasion is not available at the UEduring the SCell activation time.

In an example, if there is no reference signal received for the CSImeasurement over the delay corresponding to the minimum requirementsspecified above, then the UE may report corresponding valid CSI for theactivated SCell on the next available uplink reporting resource afterreceiving the reference signal. In an example, if there are no uplinkresources for reporting the valid CSI in subframe n+first maximum numberof subframes then the UE may use the next available uplink resource forreporting the corresponding valid CSI. In an example scenario, the validCSI may be based on the UE measurement and corresponds to any CQI valuewith the exception of CQI index=0 (out of range). In addition to CSIreporting defined above, UE may apply other actions related to theactivation command for an SCell at the first opportunities for thecorresponding actions once the SCell is activated.

In an example embodiment, the delay within which the UE may be able toactivate a deactivated licensed SCell may depend upon the UE conditions.Upon receiving SCell activation command in subframe n, the UE may becapable to transmit valid CSI report and apply actions related to theactivation command for the SCell being activated no later than n+asecond maximum number of subframes. In an example, the second maximumnumber of subframes may be defined for a scenario in which someconditions are met for the SCell. In an example, when a different set ofconditions are met for the SCell, then a different second maximum numberof subframes may be employed. The second maximum number of subframes mayalso depend on the number detection attempts needed to detect the cell.

If there is no reference signal received for the CSI measurement overthe delay corresponding to the minimum requirements specified above,then the UE may report corresponding valid CSI for the activated SCellon the next available uplink reporting resource after receiving thereference signal. If there are no uplink resources for reporting thevalid CSI in after the second maximum number of subframes then the UEmay use the next available uplink resource for reporting thecorresponding valid CSI.

FIG. 10 is an example flow diagram as per an aspect of an embodiment ofthe present invention. The flow diagram may be processed as a method.The flow diagram may be executed by a wireless device. The wirelessdevice may comprise one or more processors and memory storinginstructions that, when executed, cause the wireless device to performactions described in the flow diagram.

At least one first message maybe transmitted at 1010 indicating that awireless device supports configuration of a plurality of licensed cellsand a plurality of licensed assisted access (LAA) cells. At 1020, amedia-access-control control element (MAC CE) comprising at least oneparameter may be received in a first subframe. The parameter(s) mayinstruct the wireless device to activate at least one licensed cell andat least one LAA cell. At 1030, channel monitoring on the LAA cell(s)may be performed before a first maximum number of subframes after thefirst subframe. At 1040, channel monitoring on the licensed cell(s) maybe performed before a second maximum number of subframes after the firstsubframe. The first maximum number of subframes and the second maximumnumber of subframes may be different.

According to an embodiment, at least one second message may be received.The second message(s) may comprise configuration parameters of aplurality of cells. The plurality of cells may comprise the at least onelicensed cell and the at least one LAA cell. The configurationparameters may comprise a deactivation timer.

According to an embodiment, transmission of first valid channel stateinformation (CSI) reports may be started for the at least one LAA cellbefore the first maximum number of subframes after the first subframe.The transmission of first out of range (OOR) CSI reports for the atleast one LAA cell may be started before the valid CSI reports areavailable. The transmission of the first valid CSI reports may start afirst number of subframes after the first subframe.

According to an embodiment, the performing channel monitoring on the atleast one LAA cell may start a first number of subframes after the firstsubframe. According to an embodiment, the first maximum number ofsubframes may be smaller than the second maximum number of subframes.According to an embodiment, an activation delay of a cell may depend onwhether the cell is licensed or LAA. According to an embodiment, channelmonitoring may comprise monitoring a physical downlink control channel.

FIG. 11 is an example flow diagram as per an aspect of an embodiment ofthe present invention. The flow diagram may be processed as a method.The flow diagram may be executed by a wireless device. The wirelessdevice may comprise one or more processors and memory storinginstructions that, when executed, cause the wireless device to performactions described in the flow diagram.

At least one first message may be transmitted at 1110. The firstmessage(s) may indicate that a wireless device supports configuration ofa plurality of licensed cells and a plurality of licensed assistedaccess (LAA) cells. At 1120, a media-access-control control element (MACCE) may be received in a first subframe. The MAC CE may comprise atleast one first parameter. The parameter may instruct the wirelessdevice to activate at least one licensed cell. At 1130, a second MAC CEmay be received in a second subframe. The second MAC CE may comprise atleast one second parameter. The second parameter may instruct thewireless device to activate at least one LAA cell. At 1140, channelmonitoring may be performed on the at least one LAA cell before a firstmaximum number of subframes after the first subframe. At 1150, channelmonitoring may be performed on the at least one licensed cell before asecond maximum number of subframes after the second subframe. The firstmaximum number of subframes and second maximum number of subframes maybe different.

According to an embodiment, at least one second message, may bereceived. The second message(s) may comprise configuration parameters ofa plurality of cells. The plurality of cells may comprise the at leastone licensed cell and the at least one LAA. According to an embodiment,transmission of first valid channel state information (CSI) reports forthe at least one LAA cell may be started before the first maximum numberof subframes after the first subframe. According to an embodiment,transmission of first valid CSI reports may be started a first number ofsubframes after the first subframe. According to an embodiment,transmission of second valid CSI reports for the at least one licensedcell may be started before the second maximum number of subframes afterthe second subframe. According to an embodiment, transmission of secondvalid CSI reports for the at least one LAA cell may be started a firstnumber of subframes after the second subframe. According to anembodiment, the performing channel monitoring on the at least one LAAcell may start a first number of subframes after the first subframe.According to an embodiment, the performing channel monitoring on the atleast one licensed cell starts a first number of subframes after thesecond subframe. According to an embodiment, the first maximum number ofsubframes may be smaller than the second maximum number of subframes.

Activating a large number of carriers on dynamic bases may increase theUE power consumption, false alarm probability, and processing powerrequirements. Improved mechanisms are needed to improve efficiency inthe UE and enable fast and dynamic carrier selection/activation in a UE.Novel mechanisms may reduce UE power consumption, reduce false alarmprobability and reduce processing power requirements. Carrier selectionand activation may be enhanced to achieve fast dynamic carrier selection(or switching). A fast activation procedure for the carrier (e.g.shorter than the currently defined 24 ms) may be defined to improveefficiency.

Current SCell activation latency may include the MAC CE decoding latency(˜3-6 ms) and SCell activation preparation time (RF preparation, up to˜18 ms). Implementation of faster processes and hardware may reducethese delays. SCell MAC activation/deactivation signalling isUE-specific. Signalling overhead may be a concern especially if the cellused for transmitting the signal is a macro cell. In an exampleembodiment, a L1 procedure/indicator may be introduced and/or SCellactivation signalling may be enhanced.

Layer one signalling (e.g. PDCCH/EPDCCH from the PCell or anotherserving cell) may be implemented to signal the set of carriers that theUE may monitor for PDCCH/EPDCCH and/or measuring/reporting CSI. Controlsignalling latency may be ˜0.5-2 ms (e.g. one PDCCH transmission plus0.5 ms decoding). The DCI format may be of small size for transmissionreliability and overhead reduction. To reduce control signallingoverhead, the signalling may be a UE PCell common signalling. Theindication may be sent on a carrier that the UE is currently monitoring.

In an example embodiment, a mechanism based on a L1 indication forstarting/stopping monitoring of up to k activated carriers may beprovided. The UE may be configured with n>=k CCs. k CCs may be activatedvia MAC signalling of SCell activation/deactivation. Then based on LBTprogress over the CCs, a L1 indication is sent to inform which of the kCCs may be monitored by the UE and which may not. The UE may thenreceive data burst(s) on the monitored CCs. Another L1 indication may besent after the bursts to alter which CCs may be monitored since then,and so on. The L1 indication may be explicit (e.g., based on asignalling) or implicit (e.g., based on self scheduling and UE detectionof scheduling information on the SCell). For this example, fast carrierswitching is done among at most k CCs.

In an example embodiment, a mechanism based on a L1 signalling forstarting/stopping monitoring of up to m activated carriers (the numberof p configured carriers may be m or higher). The activated carriers maybe more than n (e.g., there may be more CCs activated for the UE thanits PDSCH aggregation capability:n). The UE is configured with p CCs,and there may be up to m CCs that are activated via MAC signalling ofSCell activation/deactivation. The UE may not monitor all the activatedCCs. The UE may monitor at most n CCs according a L1 indication (n<=m).The L1 indication needs to be explicit. For this example, fast carrierswitching may be done among possibly more than n CCs.

SCell activation/deactivation enhancements may be considered for fastcarrier switching. SCell MAC activation/deactivation signalling is a MACsignalling. MAC signalling decoding/detection (with or withoutenhancements) may be slower than L1 signalling decoding/detection. Itmay involves decoding/detection of a L1 signalling and furthermore, aPDSCH TB. If SCell activation/deactivation is carried by a L1signalling, it may still be considered for fast carrier switching. In anexample embodiment, a mechanism based on a L1 signalling foractivation/deactivation of the p configured carriers is described. TheUE is configured with p CCs. At a given subframe, at most n CCs areactivated via a L1 signalling of SCell activation/deactivation. Forinstance, based on LBT progress over the CCs, a L1 signalling is sent toinform which of the m CCs are activated. The UE may receive databurst(s) on the activated CCs. Another L1 signalling may be sent afterthe bursts to alter the activated CCs.

The control signalling may be transmitted before the eNB has gainedaccess to the carrier via LBT process. An eNB may inform the UE to start(or stop) monitoring a carrier (whether the UE would receive a burst ornot depends on the presence of PDCCH scheduling information for thecarrier). An indication for starting monitoring may be used for morethan one burst, until an indication for stopping monitoring is sent. Theindication may be sent when the eNB expects the (E)CCA is to completesoon. A purpose of the indication may be to inform a UE to start or stopmonitoring a carrier.

Transmitting the control signalling after the eNB has gained access tothe carrier may incur overhead of the reservation signal (proportionalto the control signalling latency). In an example, the maximumtransmission burst may be 4 ms. An eNB may inform the UE to receive aburst on a carrier. The eNB may send one indication for a burst. Theremay be many short bursts (e.g., one burst may last only up to 4milliseconds in certain regions). The indication may be sent after(E)CCA is completed, consuming some portion of the maximum allowedtransmission duration for a burst.

It may still be up to the network to transmit the control signallingbefore or after the channel is occupied. A UE may detect that the burstis from the serving cell (e.g. by confirming PCID or other type ofdecoding). The function of the control signalling is to indicate thatthe UE may perform DL transmission burst detection of the serving cell.If a DL burst of the serving cell is detected, UE may monitor forpossible PDCCH/EPDCCH and/or measuring the CSI on the indicated SCell.

In an example embodiment, a UE may be configured with a number ofcarriers potentially exceeding the maximum number of carriers over whichthe UE may aggregate PDSCH. RRM measurements over the configuredcarriers may be supported, e.g. RSSI-like measurement, extension ofquasi co-location concept to across collocated intra-band carriers,and/or carrier grouping. L1 indication to the UE to start monitoring acarrier, which is selected from the configured carriers by the eNB maybe supported.

An eNB may configure UE with more component carriers which maypotentially exceed the maximum number of carriers over which the UE mayaggregate PDSCH. Then eNB may activate one or more carriers among theconfigured carriers to UE by the existing signalling, e.g. MACsignalling. UE may be scheduled by the eNB on the one or more activatedcarriers dynamically based on the LBT mechanism.

A UE may switch to receive on any carrier within a set of carriersselected by the serving eNB as fast as subframe/symbol-level, while thenumber of carriers within the set may potentially exceed the maximumnumber of carriers over which the UE may aggregate PDSCH. Whichcarrier(s) the UE may switch to is per eNB indication. When the UE isindicated with the carrier(s) it may switch to, the UE may start tomonitor the indicated carrier(s), e.g. within a few subframes, and maystop monitoring other carriers. By monitoring a carrier it meant tobuffer and attempt to detect the control channels and other associatedchannels. The eNB indication may instruct the UE to switch to theindicated carrier(s) and monitor the carrier(s). The eNB may notinstruct the UE to switch to monitor on more carriers than its PDSCHaggregation capability in a given subframe. The eNB may not schedule theUE on more carriers than its PDSCH aggregation capability. SCellconfiguration enhancements may allow both semi-static and fast carrierswitching with reduced transition time. The delay associated with theSCell configuration signalling as well as the delay associated with themeasurement process may be decreased.

In an example embodiment, fast carrier switching may support UE toswitch to any carrier within a set of carriers selected by the servingeNB as fast as a few subframes/symbols. The eNB may send an indicationinstructing the UE to switch to the indicated carriers and monitor thecarriers. Then the UE may perform the switching and start monitoring theindicated carriers. The UE stops monitoring other carriers. The eNBindication may be done in L1. A L1 procedure/indicator, or anenhancements of the SCell activation signalling may be introduced.

In an example embodiment, a two phase activation process may beintroduced for SCells: MAC activation and PHY activation (also may becalled fast carrier switching, fast activation, carrier switching,and/or the like). In an example embodiment, an eNB may MAC activate anSCell in the UE by transmitting a MAC Activation Command. When an SCellin the UE is MAC activated, the UE may monitor PCell common search spacefor a physical layer activation (may also be called fast activation,cell switching, etc) command/indicator. A UE may start blind decodingfor physical layer control channels (and/or physical signals, e.g. CRS,initial signals, and/or burst indicator) when it is physical layer (PHY)activated. When an SCell in a UE is MAC activated but not yet PHYactivated, the UE may not monitor for the physical layer controlchannels on the SCell.

In an example embodiment, a UE may monitor for CSI-RS and other signalson an SCell when the SCell is MAC activated and PHY deactivated. In anexample, a UE may not monitor for CSI-RS and some other signals on anSCell when the SCell is MAC activated and PHY deactivated. Monitoringfor PHY layer signals when the SCell is MAC activated but PHYdeactivated may depend on UE/eNB implementation. A UE may not decode andmonitor physical control channels (e.g. PCFICH, (e)PDCCH) and PDSCH onSCells that is MAC activated and PHY deactivated. The signal processingrequirements on a PHY deactivated SCell may be minimum compared withwhen the SCell is PHY and MAC activated. In an example, when an SCell isMAC deactivated, the UE may not expect receiving a PHY activation forthe SCell from an eNB. An eNB may PHY activate cells that are MACactivated in a UE.

In an example embodiment, a UE may monitor PCell PDCCH common searchspace when an SCell is MAC activated. When a UE receives a PHYactivation indicator on the PCell common search space for an SCell, theUE may PHY activate the SCell. For example, when a UE receives a PHYactivation indicator for an SCell in subframe n, the UE may PHY activatethe SCell in subframe n, n+1, or n+2 depending on the PHY activationdelay.

A mechanism may be needed for the UE to determine that the PHY activatedLAA SCell is actually transmitting a signal and the corresponding celloperation may be performed for that signal (e.g. PDCCH/EPDCCHmonitoring, CSI measurement and reporting).

In an example embodiment, when an unlicensed cell is PHY activated in aUE by an eNB, the UE may need to detect the presence of the (e)PDCCHchannel. When a UE implicitly or explicitly determines that (e)PDCCH istransmitted, the UE may monitor the channel. The UE may detect thepresence of the PDCCH channel by receiving a signal on the PCell commonsearch space. The UE may detect the presence of the PDCCH signal byblind decoding the physical signals on the unlicensed cell.

For example, the blind decoding may be based on detection of whether CRSpower in a given subframe/symbol is above some certain threshold. Ablind detection may detect that the CRS is transmitted, and if CRS istransmitted the UE may monitor (e)PDCCH. In another example, the UE mayblind decode the CRS signal, or SS transmission (e.g. in subframes 0 and5), and/or CSI-RS in subframes that CSI-RS is configured. In an exampleembodiment, when a U-Cell is PHY activated, the UE may blind decode forthe presence of a burst-indicator and/or initial-signal. The UE maysearch for burst-indicator and/or initial signal to determine thebeginning of a burst. For subsequent subframes, the UE may implementblind decoding for physical signals (PCFICH, CRS, SS, etc) to detectwhether PDCCH is transmitted and whether PDCCH should be monitored. Inan example embodiment, an indicator signal may be transmitted in everysubframe in which (e)PDCCH is transmitted indicating the presence of the(e)PDCCH. UE may blind decode the indicator signal to determine whether(e)PDCCH is transmitted. The indicator signal may be a known signal orhave a known pattern or be selected from a set of known signals. Forexample, an indicator may be a combination of at least one of CSI-RS,CRS, PSS, SSS, DMRS, and/or the like.

If a burst indicator indicating the length of a burst (or end of aburst) is not transmitted (via PHY or higher layers), the UE may performblind decoding for the presence of the control channels in subsequentsubframes of a burst. The UE may not know the length of a burst andwhether a subframe was the last subframe in a burst.

In an example embodiment, PCell common search space may indicate the PHYactivation of given U-Cell to a UE. An eNB may transmit at least one RRCmessage to a UE to configure parameters related to PCell common searchspace for the transmission of indication of PHY activation of one ormore U-cell. The RRC message may comprise a signal-RNTI, a signalindicator periodicity, a signal indicator bitmap, and/or otherparameters. Some of the parameters such as signal indicator periodicity,a signal indicator bitmap, and/or other signal parameters may beoptional and may or may not be included in the RRC message depending onan eNB implementation. These fields may be included in an informationelement, e.g. called signal-LAA-Config-r13, that is included in theconfiguration of the dedicated parameters e.g. of the PCell. The IEsignal-LAA-Config may be used to specify the RNTI used for PHYactivation indicator and the subframes used for PHY activation indicatortransmission. An example information elements in an RRC connectionreconfiguration is shown below (some of the parameters may be options1):

signal-LAA-Config::=CHOICE {release NULL, setup SEQUENCE {signal-RNTIC-RNTI, signal-IndicatorPeriodicity ENUMERATED {e.g. sf10, sf20, sf40,sf80}, signal-IndicatorSubframeSet BIT STRING (SIZE(e.g. 10)),signal-other-parameters signal-Other-type of activation,e tc(forU-Cells)}}

The UE may monitor PCell common search space for a common search spacefor a DCI scrambled with signal-RNTI according to common search spacesearch process. If the RRC comprises signal-IndicatorPeriodicity-r13,the UE may configure the periodicity to monitor PDCCH with signal-RNTI.For example, value sf10 corresponds to 10 subframes, sf20 corresponds to20 subframes and so on.

If the RRC comprises signal-IndicatorSubframeSet-r13, the UE mayconfigure the subframe(s) to monitor PDCCH with signal-RNTI within theperiodicity configured by signal-indicatorPeriodicity (if periodicity isconfigured). If periodicity is not configured, the periodicity may bethe length of the bit string of signal-IndicatorSubframeSet-r13 in termsof subframes. The example, 10 bits correspond to subframes in the lastradio frame within each periodicity (e.g. if periodicity is notconfigured, it is 10 subframe). For example, the left most bit is forsubframe 0 and so on. A bit can be of value 0 or 1. In an exampleimplementation, the value of 1 means that the corresponding subframe isconfigured for monitoring PDCCH with signal-RNTI, and the value of 0means otherwise. In case of TDD as PCell, only downlink subframesindicated by the DL/UL subframe configuration in SIB1 may be configuredfor monitoring PDCCH with signal-RNTI. In case of FDD as PCell, any ofthe ten subframes may be configured for monitoring PDCCH withsignal-RNTI. The IE signal-other-parameters may comprise one or morecell configuration parameters, for example, the parameter may determinePHY activation type, CSI signal format, activation duration, startingsymbol, type, and/or for other cell configuration parameters.

The example embodiment, provides flexibility in transmission of PHYactivation indicator configuration in addition to providing batterysaving and processing power saving opportunities. In R-12 and before,activation command can be transmitted in any subframe. Following R-12principles, there would be no reason to transmit an additional bitmapand/or period for the common search space monitoring. In a U-Cell, theeNB may not be able to PHY activate a U-Cell for a UE in a givensubframe according to the RRC configuration. The indicator transmittedin PCell common search space provides flexibility to transmit PHYactivation in a configured subframe. Transmitting PHY activation in anysubframe, may require UE to search common search space in everysubframe, which requires extra processing. The bitmap (and/or period)provides flexibility in limiting the subframes, in which UE needs tosearch for PHY activation. In an example embodiment the bitmap may beconfigured as [1100011000]. In the example, PHY activation may betransmitted in subframes 0, 1, 5, and 6. In an example embodiment, thebitmap and periodicity may not be implemented for PHY activationindicator.

In release 13 and beyond up to 32 cells (or more) may be configured, dueto limited DCI size in common search space, a DCI may not be largeenough to transmit PHY activation indication for all the cells. In anexample, the bitmap and period may be configured for a U-cell (insteadof for all U-cells), and the bitmap and/or period may allow the eNB todivide the subframes in multiple sets, a first subframe set indicated bya first bitmap may be for transmitting indicator for a first subset ofcells, and a second subframe set indicated by a second bitmap may be fortransmitting indicator for a second subset of cells. In this example,the subframe bitmap may be a cell specific parameter instead of being aUE specific parameter as shown in the example above.

The one or more RRC messages may comprise one or more parameters for aU-cell to configure the format of the DCI and how the bits in the DCImay be interpreted. In an example embodiment, one or more parameters foran LAA cell may comprise signal-DCI-Index-r13 and/orOther-signal-parameters. For example, signal-DCI-Index-r13 may determinethe index of the bits in the DCI control packet associated with a givenU-cell. For example, when the index is 4, it may indicate the fourthsubset of bits in the DCI corresponds to the given U-cell for the UE.The IE signal-other-parameters may comprise one or more signalconfiguration parameters, for example, the parameter may determinesignal format, activation type, duration. An example, RRC informationelement for a given U-cell is shown below:

signal-LAA-SCell::=CHOICE {release NULL,setup,SEQUENCE {signal-DCI-IndexINTEGER (1..xx), Other-signal-parameters Other-signal-Parameters}}

DCI format employed in PCell common search space and employed for PHYactivation transmission indication is shown as bellow. The followinginformation may be transmitted by means of the DCI format includingmultiple set of k bits. For example, the signal transmissionconfiguration indication may comprise {signal number 1, signal number 2,. . . , signal number I}.

Where a signal number is k bit(s), and index I=floor(L/k), wherein L isequal to the payload size of DCI (for example, DCI format 1C used forvery compact scheduling of one PDSCH codeword). K may be 1 or greaterthan 1, e.g. 2, 3, or 4. The parameter signal-DCI-Index provided byhigher layers determines the index to the signal indication for aserving cell. In an example implementation, zeros may be added until thesize is equal to that of format 1C used for very compact scheduling ofone PDSCH codeword.

In an example configuration, DCI {1,1,0,0,00000000} may be transmitted,which indicates the PHY activation is triggered for the first and secondconfigured cell, and is not triggered for the third and fourthconfigured cell (according to signal-DCI-Index-r13 for cells),additional zeros may be padding. In an example, the cell PHY activationmay be UE specific. The first bit may correspond to PHY activation of afirst cell in a first UE, a the second bit may correspond to the PHYactivation of a second cell in a second UE. The eNB may configure theindexes for different UEs according to eNB internal activationmechanism.

In another example, DCI {2,1,0,3,000000} may be transmitted, whichindicates the PHY activation type 2 is triggered for the first cell PHYactivation type 1 is triggered for the second configured cell, and noPHY activation is triggered for the third cell and PHY activation type 3is triggered for the fourth configured cell (according tosignal-DCI-Index-r13 for cells), additional zeros may be padding. PHYactivation types may be determined according to a pre-definedconfiguration table or RRC configuration parameters.

In an example embodiment, more than 1 bit may be used for signal number.More than 1 bit may be used for signal number, e.g., to determine aspecific configuration for the transmitted signal, or for indication ofa type of PHY activation. For example, when signal number is 2 bits,each indication could be for one of the four configurations.

UEs may be grouped using the same or different RNTIs or indexes forsignal transmission. One UE may have multiple RNTI for different cellsor different purposes, e.g. a first RNTI may be for a first subset ofcells, and another RNTI may be for a second subset of cells. Thisconfiguration of RNTI for different UEs and different cells depends oneNB implementation and the parameters in RRC messages. An eNB may employRNTI, subframe and/or index resources by transmitting RRC configurationmessages to the UE. In an example embodiment, a first set of UEs may beconfigured with one RNTI, and a second set of the UEs may be configuredwith a second RNTI for PHY activation indication. In an implementationexample, different subsets of UEs could monitor different subset ofsubframes (controlled by bitmap and/or period) for PHY activationindication using the same RNTI. PHY activation indicator may be aconfigured as a multicast message to many UEs by the eNB. This may beperformed by configuring the same parameters for a given cell for agroup of UEs. PHY activation indicator may be a configured as a unicastmessage to a UE by the eNB. This may be performed by configuringdifferent parameters for a given cell for different UEs. This mechanismdescribed in example embodiments provides flexibility and eNB mayconfigure the parameters selectively to enhance network capacity andefficiency.

A UE may monitor the PCell common search space, when the common searchspace is configured with signal-RNTI and at least one cell with thisconfiguration is MAC activated. When for example all U-cells configuredwith signal-RNTI are MAC deactivated, the UE may not monitor the commonsearch space. If a UE receives a MAC activation command in subframe nfor a first cell, the UE may start monitoring the common search spacefor a DCI associated with signal-RNTI at subframe n+k, wherein k is apredefined number for example, 3, 6 or 8. K may depend on cellactivation delay.

If a UE is configured by higher layers to decode PDCCHs with the CRCscrambled by the signal-RNTI, the UE may decode the PDCCH according tothe common search space configuration. The subframes in which the UEmonitors PDCCH with CRC scrambled by signal-RNTI are configured byhigher layers (RRC). If UE is not configured with the parametersignal-LAA-Config-r13 for any activated serving cell, the UE is notexpected to monitor PDCCH with CRC scrambled by signal-RNTI.

Example embodiment may be extended to transmit additional indications toa UE on PCell common search space for an SCell. For example, indicationsfor an SCell may include burst indication, CSI transmission, burstduration, uplink subframes, uplink duration, downlink/uplinkconfiguration, subframe configuration, and/or the like. The DCI formatfor each of these indications may be different.

In an example, a new DCI format may be defined. For example, DCI formatmay include an initial format bits determining the type, format and thepurpose of the DCI, and the additional bits in the DCI may beinterpreted according to the format bits. For example, DCI format may be{DCI type, indication number 1, indication number 2, indication number3, . . . }. When DCI type is zero, the indication numbers may be for CSItransmission according to the configured index for CSI transmission onU-Cell for a UE. When DCI type is one, the indication numbers may be forPHY activation of a U-cell in a UE according to the configured index fora U-Cell activation for a UE. For example, other DCI types may bedefined for DRS transmission, burst indicator, burst duration, (e)PDCCH,and other signal examples provided in the specification.

An RRC message may comprise configuration parameters of the searchspace, e.g., RNTI, periodicity and/or subframe bitmap for theindication. An indication may have its own RNTI, or differentindications may share the same RNTI. It is up to eNB to configure commonsearch resources (RNTI, subframe, indexes) for different types ofindications. A UE may be configured with an index for a Cell (RRC maycomprise an index) to determine the index of the bits in the DCIemployed for the indication of the cell for the UE.

For example, RNTI of 3 in a first subset of subframe may be configuredfor transmission of CSI indication for a first subset of UEs on firstsubset of cells according to DCI format 1. RNTI of 4 in a second subsetof subframe may be configured for transmission of fast activationindication for a second subset of UEs on second subset of cellsaccording to DCI format 2. It is up to eNB implementation to employcommon search space resources according to the available RRC messageformat and UE capabilities.

The process described above may also be employed for PHY deactivation ofan SCell in a UE. For example bit value of 1 in a DCI may indicate PHYactivation of an SCell and bit value of 0 in a DCI may indicate PHYdeactivation of an SCell.

In an example embodiment, cells in the same band transmitted from thesame transmission point, or cells within a configured group may be PHYactivated or PHY deactivated together. This could be an implementationoption in an eNB. In another example embodiment, the same DCI indexcould be assigned to cells within a group. This may imply that the samebits apply to the cells of the same group. In an example, if a cell isMAC deactivated within a group, the cell may not be PHY activated.

In an example embodiment, a DCI transmitted in the dedicated searchspace may be transmitted to indicate PHY activation for an SCell. Thededicated DCI may be transmitted using the C-RNTI employed fortransmission of DCI in the dedicated search space of the PCell or anSCell cross carrier scheduling the SCell. The UE may monitor a dedicatedsearch space for a DCI scrambled with C-RNTI according to the dedicatedsearch space search process. In an example implementation, a new DCI maybe introduced for PHY activation of an SCell. In an exampleimplementation, a new field may be introduced to a DCI for PHYactivation of an SCell. The new DCI or the new field may include abitmap, wherein a bit (or a set of bits) may be employed for PHYactivation and other indications of an SCell. The correspondence betweenthe bits (the index of the bits) and the SCell may be predefined. Forexample, the order of the bits in the bitmap may be according to thecell index of the configured cells. In an example embodiment, a bitmapformat similar to the MAC activation bitmap may be employed. In anexample embodiment, the bitmap may include 8 bits, when 8 cells areconfigured, or when the highest cell index is smaller than (or equal) to8. The bitmap may include 32 bits, when the highest cell index is largerthan 8.

In an example implementation, the correspondence between the bits andthe SCell may be configured via an RRC message transmitted from the eNBto the UE. The RRC message may comprise an index for an SCellidentifying the index of the bit(s) in the DCI that corresponds to thecell. When the UE receives a dedicated DCI for PHY activation and/ordeactivation of a cell, the UE may PHY activate the cell.

In an example embodiment, a more generic dedicated DCI may be introducedto indicate cell PHY activation and other cell and UE specificindication. For example, a format of the DCI may be employed for burstindication on a given cell. A format of the DCI may be employed foraperiodic CSI triggering for a UE on a given cell. Other triggermechanism using dedicated DCI may be implemented.

In an example embodiment, when a cell is PHY activated, the UE and eNBmay restart the MAC sCellDeactivationTimer timer corresponding to theSCell. When a UE receives a PHY activation command from the eNB insubframe n, the UE may restart the MAC sCellDeactivationTimer timercorresponding to the SCell in subframe n, in subframe n+k (wherein k isa predefined number, e.g. 1, 2, 3). This process may ensure that the UEmay not MAC deactivate an SCell when sCellDeactivationTimer timer isclose to the expiry and the UE has PHY activated an SCell.

In an example embodiment, when sCellDeactivationTimer timercorresponding to the SCell expires, the UE may deactivate the SCell bydeactivating both PHY and MAC layers. The UE may perform RRM measurementfor a MAC/PHY deactivated SCell. When a UE receives a PHY deactivationindication from the eNB, the UE may deactivate the PHY layer, but maynot change the status of the MAC activation.

In an example embodiment, a PHY deactivation timer may be configured foran SCell. The PHY deactivation may be controlled by a PHY deactivationtimer. The UE may receive an RRC message configuring the PHYdeactivation timer for an SCell of a UE. In an example embodiment, acell may have its own configured PHY deactivation timer, but a singlePHY deactivation timer value may be applicable to more than one SCell(for example, all U-Cells, or all Scells). In an example embodiment, afirst PHY deactivation timer value may be applicable to U-cells and asecond first PHY deactivation timer value may be applicable to licensedcells. An RRC comprising the timer values may be transmitted to a UE toconfigure the PHY deactivation timers.

The UE may start a PHY deactivation timer for an SCell, when the UEreceives a PHY activation indicator. For example, when a UE receives aPHY activation indicator in subframe n for an SCell, the UE may startthe PHY deactivation timer for the SCell in the same subframe (or aftera certain delay, e.g. 1, 2, 3 or 4 subframes).

In an example embodiment, if (e)PDCCH on the activated SCell indicatesan uplink grant or downlink assignment; or if PDCCH on the Serving Cellscheduling the activated SCell indicates an uplink grant or a downlinkassignment for the activated SCell: the UE may restart the PHYdeactivation timer associated with the SCell. The UE may also restartthe sCellDeactivationTimer of the SCell. In an example embodiment,additional conditions may be defined for restarting the PHY deactivationtimer. For example, an SCell PHY deactivation timer may be restartedwhen A-CSI is triggered on the Cell, or a downlink or uplink burst isstarted on the SCell. The timer may be maintained in both the UE and theeNB.

In an example embodiment, MAC sCellDeactivationTimer value may begreater than PHY deactivation timer. This may cause the UE stay MACactivated as long as the SCell is PHY activated, or may reduce theprobability of such event. PHY activation timer and MACsCellDeactivationTimer are running when an SCell is both PHY and MACactivated. When PHY deactivation timer expires, the UE may be PHYdeactivated. The UE may remain MAC activated and monitor the searchspace for receiving a PHY activation indication for the SCell. When MACactivation timer expires, or a UE receives a MAC deactivation command,the UE may stop the PHY activation timer (if it is running) of the SCelland MAC deactivate the SCell.

In an example embodiment, SCell PHY deactivation may be performed when aUE receives a PHY deactivation indicator for the SCell from the eNB.SCell PHY deactivation may be performed when the PHY deactivation timerof an SCell expires in a UE. When a UE receives a PHY deactivationindicator for an SCell from the eNB, the UE may stop the PHYdeactivation timer and PHY deactivate the SCell.

In this specification, “a” and “an” and similar phrases are to beinterpreted as “at least one” and “one or more.” In this specification,the term “may” is to be interpreted as “may, for example.” In otherwords, the term “may” is indicative that the phrase following the term“may” is an example of one of a multitude of suitable possibilities thatmay, or may not, be employed to one or more of the various embodiments.If A and B are sets and every element of A is also an element of B, A iscalled a subset of B. In this specification, only non-empty sets andsubsets are considered. For example, possible subsets of B={cell1,cell2} are: {cell1}, {cell2}, and {cell1, cell2}.

In this specification, parameters (Information elements: IEs) maycomprise one or more objects, and each of those objects may comprise oneor more other objects. For example, if parameter (IE) N comprisesparameter (IE) M, and parameter (IE) M comprises parameter (IE) K, andparameter (IE) K comprises parameter (information element) J, then, forexample, N comprises K, and N comprises J. In an example embodiment,when one or more messages comprise a plurality of parameters, it impliesthat a parameter in the plurality of parameters is in at least one ofthe one or more messages, but does not have to be in each of the one ormore messages.

Many of the elements described in the disclosed embodiments may beimplemented as modules. A module is defined here as an isolatableelement that performs a defined function and has a defined interface toother elements. The modules described in this disclosure may beimplemented in hardware, software in combination with hardware,firmware, wetware (i.e hardware with a biological element) or acombination thereof, all of which are behaviorally equivalent. Forexample, modules may be implemented as a software routine written in acomputer language configured to be executed by a hardware machine (suchas C, C++, Fortran, Java, Basic, Matlab or the like) or amodeling/simulation program such as Simulink, Stateflow, GNU Octave, orLabVIEWMathScript. Additionally, it may be possible to implement modulesusing physical hardware that incorporates discrete or programmableanalog, digital and/or quantum hardware. Examples of programmablehardware comprise: computers, microcontrollers, microprocessors,application-specific integrated circuits (ASICs); field programmablegate arrays (FPGAs); and complex programmable logic devices (CPLDs).Computers, microcontrollers and microprocessors are programmed usinglanguages such as assembly, C, C++ or the like. FPGAs, ASICs and CPLDsare often programmed using hardware description languages (HDL) such asVHSIC hardware description language (VHDL) or Verilog that configureconnections between internal hardware modules with lesser functionalityon a programmable device. Finally, it needs to be emphasized that theabove mentioned technologies are often used in combination to achievethe result of a functional module.

The disclosure of this patent document incorporates material which issubject to copyright protection. The copyright owner has no objection tothe facsimile reproduction by anyone of the patent document or thepatent disclosure, as it appears in the Patent and Trademark Officepatent file or records, for the limited purposes required by law, butotherwise reserves all copyright rights whatsoever.

While various embodiments have been described above, it should beunderstood that they have been presented by way of example, and notlimitation. It will be apparent to persons skilled in the relevantart(s) that various changes in form and detail can be made thereinwithout departing from the spirit and scope. In fact, after reading theabove description, it will be apparent to one skilled in the relevantart(s) how to implement alternative embodiments. Thus, the presentembodiments should not be limited by any of the above describedexemplary embodiments. In particular, it should be noted that, forexample purposes, the above explanation has focused on the example(s)using FDD communication systems. However, one skilled in the art willrecognize that embodiments of the invention may also be implemented in asystem comprising one or more TDD cells (e.g. frame structure 2 and/orframe structure 3-licensed assisted access). The disclosed methods andsystems may be implemented in wireless or wireline systems. The featuresof various embodiments presented in this invention may be combined. Oneor many features (method or system) of one embodiment may be implementedin other embodiments. Only a limited number of example combinations areshown to indicate to one skilled in the art the possibility of featuresthat may be combined in various embodiments to create enhancedtransmission and reception systems and methods.

In addition, it should be understood that any figures which highlightthe functionality and advantages, are presented for example purposesonly. The disclosed architecture is sufficiently flexible andconfigurable, such that it may be utilized in ways other than thatshown. For example, the actions listed in any flowchart may bere-ordered or only optionally used in some embodiments.

Further, the purpose of the Abstract of the Disclosure is to enable theU.S. Patent and Trademark Office and the public generally, andespecially the scientists, engineers and practitioners in the art whoare not familiar with patent or legal terms or phraseology, to determinequickly from a cursory inspection the nature and essence of thetechnical disclosure of the application. The Abstract of the Disclosureis not intended to be limiting as to the scope in any way.

Finally, it is the applicant's intent that only claims that include theexpress language “means for” or “step for” be interpreted under 35U.S.C. 112, paragraph 6. Claims that do not expressly include the phrase“means for” or “step for” are not to be interpreted under 35 U.S.C. 112.

1. A wireless device comprising: one or more processors; and memorystoring instructions that, when executed by the one or more processors,cause the wireless device to: receive, from a base station, one or moremessages comprising configuration parameters of a cell, wherein theconfiguration parameters comprise: a first value for a first timer; anda second value for a second timer, wherein the second timer is formonitoring a downlink control channel; receive a medium-access control(MAC) control element (CE) indicating an activation of the cell; basedon the MAC CE: activate the cell; and start the first timer; receivefirst downlink control information (DCI) indicating monitoring thedownlink control channel; based on the first DCI: start the secondtimer; and monitor the downlink control channel; and receive, while thefirst timer and the second timer are both running, second DCI comprisingone or more of a downlink assignment or an uplink grant.
 2. The wirelessdevice of claim 1, wherein the instructions, when executed by the one ormore processors, further cause the wireless device to restart, based onthe receiving the second DCI, the second timer.
 3. The wireless deviceof claim 1, wherein the instructions, when executed by the one or moreprocessors, further cause the wireless device to: stop the second timer;and stop monitoring of the downlink control channel; wherein stoppingthe second timer and stopping the monitoring the downlink controlchannel are based on one or more of: the first timer expiring; orreceiving a second MAC CE, wherein the second MAC CE indicates adeactivation of the cell.
 4. The wireless device of claim 1, wherein theinstructions, when executed by the one or more processors, further causethe wireless device to stop, based on the second timer expiring andwhile an activation status of the cell is maintained, monitoring of thedownlink control channel.
 5. The wireless device of claim 1, wherein theinstructions, when executed by the one or more processors, further causethe wireless device to, based on the cell being active, perform at leastone of: measuring one or more reference signals; or monitoring a seconddownlink control channel for receiving the first DCI.
 6. The wirelessdevice of claim 5, wherein one of the one or more reference signals is achannel state information reference signal.
 7. The wireless device ofclaim 1, wherein the instructions, when executed by the one or moreprocessors, cause the wireless device to measure one or more referencesignals after activating the cell.
 8. The wireless device of claim 1,wherein the first timer is associated with physical layer deactivation.9. The wireless device of claim 1, wherein the second timer isassociated with secondary cell deactivation.
 10. A base stationcomprising: one or more processors; and memory storing instructionsthat, when executed by the one or more processors, cause the basestation to: transmit, to a wireless device, one or more messagescomprising configuration parameters of a cell, wherein the configurationparameters comprise: a first value for a first timer; and a second valuefor a second timer, wherein the second timer is associated with thewireless device monitoring a downlink control channel; transmit amedium-access control (MAC) control element (CE) indicating anactivation of the cell; based on the MAC CE: activate the cell for thewireless device; and start the first timer; transmit first downlinkcontrol information (DCI) indicating monitoring the downlink controlchannel; based on the first DCI, start the second timer associated withthe wireless device monitoring the downlink control channel; andtransmit, while the first timer and the second timer are both running,second DCI comprising one or more of a downlink assignment or an uplinkgrant.
 11. The base station of claim 10, wherein the instructions, whenexecuted by the one or more processors, further cause the base stationto, based on the second DCI, restart the second timer.
 12. The basestation of claim 10, wherein the instructions, when executed by the oneor more processors, further cause the base station to stop the secondtimer based on one or more of: the first timer expiring; or transmittinga second MAC CE indicating deactivation of the cell.
 13. The basestation of claim 10, wherein the first timer is associated with physicallayer deactivation.
 14. The base station of claim 10, wherein the secondtimer is associated with secondary cell deactivation.
 15. Anon-transitory computer-readable medium storing instructions that, whenexecuted, configure a wireless device to: receive, from a base station,one or more messages comprising configuration parameters of a cell,wherein the configuration parameters comprise: a first value for a firsttimer; and a second value for a second timer, wherein the second timeris for monitoring a downlink control channel; receive a medium-accesscontrol (MAC) control element (CE) indicating an activation of the cell;based on the MAC CE: activate the cell; and start the first timer;receive first downlink control information (DCI) indicating monitoringthe downlink control channel; based on the first DCI: start the secondtimer; and monitor the downlink control channel; and receive, while thefirst timer and the second timer are both running, second DCI comprisingone or more of a downlink assignment or an uplink grant.
 16. Thenon-transitory computer-readable medium of claim 15, wherein theinstructions, when executed, configure the wireless device to restart,based on the receiving the second DCI, the second timer.
 17. Thenon-transitory computer-readable medium of claim 15, wherein theinstructions, when executed, configure the wireless device to: stop thesecond timer; and stop monitoring of the downlink control channel;wherein stopping the second timer and stopping monitoring of thedownlink control channel are based on one or more of: the first timerexpiring; or receiving a second MAC CE, wherein the second MAC CEindicates a deactivation of the cell.
 18. The non-transitorycomputer-readable medium of claim 15, wherein the instructions, whenexecuted, configure the wireless device to stop, based on the secondtimer expiring and while an activation status of the cell is maintained,monitoring of the downlink control channel.
 19. The non-transitorycomputer-readable medium of claim 15, wherein the instructions, whenexecuted, configure the wireless device to, based on the cell beingactive, perform at least one of: measuring one or more referencesignals; or monitoring a second downlink control channel for receivingthe first DCI.
 20. The non-transitory computer-readable medium of claim19, wherein one of the one or more reference signals is a channel stateinformation reference signal.
 21. The non-transitory computer-readablemedium of claim 15, wherein the instructions, when executed, configurethe wireless device to measure one or more reference signals afteractivating the cell.
 22. The non-transitory computer-readable medium ofclaim 15, wherein the first timer is associated with physical layerdeactivation.
 23. The non-transitory computer-readable medium of claim15, wherein the second timer is associated with secondary celldeactivation.
 24. A non-transitory computer-readable medium storinginstructions that, when executed, configure a base station to: transmit,to a wireless device, one or more messages comprising configurationparameters of a cell, wherein the configuration parameters comprise: afirst value for a first timer; and a second value for a second timer,wherein the second timer is associated with the wireless devicemonitoring a downlink control channel; transmit a medium-access control(MAC) control element (CE) indicating an activation of the cell; basedon the MAC CE: activate the cell for the wireless device; and start thefirst timer; transmit first downlink control information (DCI)indicating monitoring the downlink control channel; based on the firstDCI, start the second timer associated with the wireless devicemonitoring the downlink control channel; and transmit, while the firsttimer and the second timer are both running, second DCI comprising oneor more of a downlink assignment or an uplink grant.
 25. Thenon-transitory computer-readable medium of claim 24, wherein theinstructions, when executed, configure the base station to, based on thesecond DCI, restart the second timer.
 26. The non-transitorycomputer-readable medium of claim 24, wherein the instructions, whenexecuted, configure the base station to stop the second timer based onone or more of: the first timer expiring; or transmitting a second MACCE indicating deactivation of the cell.
 27. The non-transitorycomputer-readable medium of claim 24, wherein the first timer isassociated with physical layer deactivation.
 28. The non-transitorycomputer-readable medium of claim 24, wherein the second timer isassociated with secondary cell deactivation.